Zero-Sum is a roguelike card game for Android, played in landscape: you build your deck, put creatures on the board and turn every attack into a cascade of damage that can run into the millions.
Forge your deck, throw your threats on the table and unleash an unstoppable cascade of damage.
How to play
Each battle lasts 5 turns and you have to bring the enemy's life to zero. Mana goes up every turn: you play creatures, spells, enchantments and lands, and at the end of the turn all your creatures attack together.
Damage is worked out as Power × Mult, step by step: creatures in board order, this turn's spells, cost formations (pairs, triads, curves, as in poker), cards held in hand and relics, one by one. Before you attack, you already know how much you'll deal and whether the blow is lethal.
The enemy answers with a counterattack, which your creatures can block. Your life carries over from battle to battle, so every choice counts.
A run
A run has 8 antes on a map full of choices: normal, Guard or Elite battles, the Shop, events, the Camp, Treasure, the Sanctuary, the Arena and other stops. Every 4 antes a boss appears with a rule of its own, and it awakens into a second phase at half life.
Between battles you buy cards, open boosters, collect relics, put seals on your cards and improve your deck. Beat ante 8 and you can carry on in Endless mode for as long as you can last, choosing a Pact every 4 antes: 1 of 3 curses, and the worst ones pay more gold.
Game modes
Campaign: 20 decks in 4 books, each with 8 Planar Stakes of difficulty and medals.
Quick Run: 4 antes with any deck.
Free Mode: any deck, including the ones you build.
Arena Draft: build your deck on the spot by opening boosters.
Story: 20 chapters in 3 books, with bosses who talk.
Challenges: 16 runs with special rules and up to 3 stars each.
Archmage's Tower: floor after floor, with no shop or map, and a boss every 5 floors.
Boss Rush: the bosses you have beaten, back to back, with a medal for your average turns.
Learn and Train: Mage School (13 lessons), 25 Puzzles and Training, against the Dummy or a boss you have beaten.
Progression and collection
Easy, Normal, Hard and Nightmare difficulties.
Deck levels with variants, a Talent tree and card mastery (Bronze, Silver and Gold).
125 achievements and Statistics with charts and your run history.
A Collection with cards, relics, the Bestiary, the Gallery of illustrations, the Mage's Journal and Cosmetics: card backs, frames, board mats and final-blow effects.
A Deck Builder, with codes to share.
Content
487 cards and 20 starter decks: creatures, spells, enchantments, lands and double-faced cards.
87 relics, 65 enemies and bosses, 45 events (9 of them in 3 chain stories) and 14 Planar Weathers.
6 Patrons, 8 card seals, 11 formations and dozens of keywords and mechanics.
More than 800 illustrations and original music on every screen, which builds up during the attack.
Comfort and accessibility
Saves automatically after every play, with 6 save slots; you can undo plays within the turn and purchases in the shop.
Animation speed, 1- or 2-tap play, one-hand mode and a side swap for left-handers.
Colour-blind mode, high contrast, large text, reduce motion and performance mode for slower phones.
In Portuguese and English.
Playable without internet: the connection is only used to check for updates. When there's a new version, the game lets you know and installs it without losing your progress.
Images
How to install the APK
Download the file.
Open it on your phone and allow installs from this source when Android asks.
Install and play.
For now, the mobile games are Android-only. They will come to Google Play and the App Store when they are officially published.
Technology
Zero-Sum is made in Godot Engine 4.3, an open-source game engine (MIT licence), and the whole game is written in GDScript. The tools around it (cards, illustrations, music and updates) are in Python, and the build runs on GitHub.
Language
What it does
Engine or tool
GDScript
The whole game: rules, battles, interface, animations, saves and updates (about 41,000 lines, plus 9,000 of automated tests)
Godot Engine 4.3
Godot Shading Language (similar to GLSL)
6 shaders: holographic shine on the cards, attack flames, golden titles, the reflection on the enlarged card, window blur and a band of light on the card backs
Godot 4.3, Mobile renderer (Vulkan)
JSON
Content and translations: cards, decks, relics, enemies, events, achievements and story (more than 30 files)
Read by the game; can be updated without reinstalling
Python 3
Tools (about 8,000 lines): generating the cards from the design document, translations, cropping and optimising the illustrations, synthesising the music and sounds, and signing the updates
Pillow, NumPy, SciPy, FFmpeg, cryptography and Playwright
YAML
Automatic APK build and a test on an Android emulator for every version
GitHub Actions, with the godot-ci 4.3 Docker image
SVG, HTML and CSS
App icon and splash screen
Drawn as vectors and converted with Chromium (Playwright)
Platform: Android (64-bit APK for ARM processors), landscape screen based on 1280×720 that adapts to any aspect ratio.
App updates: each version is built on GitHub Actions and published on GitHub; the game compares it with the installed version and installs over it, without losing your progress.
Content updates: new data arrives without reinstalling, through GitHub Pages, with an ECDSA P-256 digital signature checked on the phone.
Automated tests: a smoke test for every version, a bot that plays 160 runs to measure balance, automatic screenshots and a boot test on an Android emulator.
Illustrations: created with Google Gemini from original descriptions and optimised in Python (WebP and thumbnails).
Music and sound effects: composed and synthesised in code (Python), with no samples.
Fonts: Inter, Lora and New Rocker, under the SIL Open Font License.
Release notes
Spoiler: notes for every version (24)
0.17.0
current version
New
Archmage's Tower: floor after floor, with no shop or map. After each floor you choose a card, a relic or a rest; every 5 floors there is a boss. Your highest floor is saved.
Boss Rush: the campaign bosses you have already beaten, back to back, with any deck you like and 30% healing between battles. A medal for your average turns.
Boss training: in Training you pick a boss you have already beaten and fight it with its rule, abilities and rituals, without touching your run.
Endless Pacts: every 4 antes you choose 1 of 3 curses, and the worst ones pay more gold.
8 new enemies, 2 of them bosses: Looking-Glass Weaver, Bronze Colossus, Drought Druid, Hungry Shade, Swarm Queen, Frost Sentinel, Ritual King and Lady of a Thousand Hands.
Chain stories: 3 stories in 3 parts throughout the run; what you choose in one part changes the next ones and the final reward.
Mage's Journal, in the JOURNAL tab of the Collection: 24 pages of the Plane's story, which open as you beat bosses, finish chapters and discover rare cards.
9 new achievements, with a card back, a frame and a board mat.
Changed
The update APK has the version in its name (ZeroSum_v0.17.0.apk) and the notice tells you which file to open.
Training has two targets: the Dummy or a boss.
The Campaign shows how many decks it has (it said 18, written by hand; there are 20).
Fixed
Boss rituals never actually started in battles.
On the Campaign screen, the deck variant text was squeezed next to the card backs.
Old place names and one card's text that had stayed in the game.
0.16.1
New
Collection with five tabs: cards now with their illustrations, relics, Bestiary, Gallery and Cosmetics, in a grid with a side panel.
Gallery of the illustrations you have discovered (cards, enemies, relics and places) and the “ART ONLY” button, also on the enlarged card.
Cosmetics: see every card back, frame, board mat and effect, the ones you are missing and how to earn them, and pick one with USE.
Card backs for each deck (earned by taking the deck to level 4) and holographic backs for whoever beats Nightmare on Stake 8.
Choose a card back for each deck, in the Campaign and in the Deck Builder; the library and the screen transition use it, with a passing shine.
Talent tree, achievements as medals with a progress bar, and Statistics with a chart per deck and a history with the ante bar.
Animated intro when you open the game (tap to skip) and a menu sky that follows the time of day.
Mythic cards with a living illustration and embers.
Changed
Deck Builder with the illustrations, colour buttons with the mana symbol and the deck shown in strips with the art.
Interludes with the illustration zooming in and the story written letter by letter.
Map: the path draws itself as you arrive, the next act stays in the fog, and life, gold and potions appear with icons and images.
The screen transition changes with the destination: a card for battle, fog for the map, a coin for the shop and a circle for events.
A notification of its own, with an image and a sound, when you earn a cosmetic.
Lighter Collection: it only draws the cards on screen, with smaller, sharper thumbnails.
Fixed
The Android “back” button closed the window and left the screen at the same time.
An old place name that had stayed in the Story.
0.16.0
New
New shop: real cards with prices (tap to pick, BUY to buy, hold your finger to see it enlarged), relics in medallions, potions and Vouchers with images, and services with icons.
In the shop: a booster that opens like a pack, new offers that flip over, a SOLD stamp, interest coming in as coins and your relics in slots with SELL.
The Merchant and the Blind Merchant with portraits and lines; MENU in the shop (the shop is saved just as it is).
Battle: a camera that follows the cascade, banners in a band of light, synergy arrows, a glow on the card that gives you lethal, bosses that shatter and a rewards screen at the end.
Bosses with three expressions (normal, hurt and angry) and illustrations for events and stops.
New windows: relics with their image and set, Patron, weather, a pause screen with a run summary and card lists with tabs.
On a slow phone, the game suggests performance mode (once).
Changed
Bigger enemy, with its illustration faded in the background and its intent above the portrait; boss life in segments.
Graveyard and library as piles (the card leaves the pile and flips), spells as miniatures, marked slots on the board, the Chain as links and a redesigned coin.
Custom icons across the game, buttons that shrink and vibrate when you touch them, and gold plaques in the shop, on the map and in windows.
Lighter on your phone: 30 FPS while you think, menus in low-power mode and images loaded before the battle.
Fixed
Long event options are no longer cut off.
0.15.1
New
Illustrations for the 33 new cards from 0.15.0 (including the 6 mythics) and for the 12 new relics: every card and relic now has artwork.
0.15.0
New
12 new mechanics: Dexterity, Delirium, Domain, Persist, Veterans, Energy, Crown, Blood Mana, Overkill turns into gold, Weak point, boss Rituals and Constellations in the shop.
33 new cards (6 mythics earned with achievements), 12 relics and 3 seals (Guardian, Mirror and Fortune).
7 new card backs, earned with achievements (Pumpkin Night until 2 November, Snowflake in December).
WHY DID I LOSE? at the end of a lost run: 2 to 3 tips based on the battle.
In the shop, ↩ UNDO the last purchase, service or sale.
In the battle pause menu, EXIT TO MENU without abandoning the run.
Changed
New, original names for cards, decks (now factions), characters and places: Patrons, Blood Mana, Seal of Corruption and Prismatic Convergence, among others.
The battle saves itself after every play.
In Endless, big numbers are shown abbreviated (tap the enemy's life to see the exact value).
Redesigned mana symbols (star, waves, moon, spark and leaf) and the 8 seals in two columns.
Fixed
UNDO and saving mid-turn no longer forget the spells you cast.
Life in some puzzles adjusted to match the best possible attack.
0.14.1
New
Cards with the “Art in focus” look: the illustration fills the whole top of the card, with the name over it.
Cost in a glowing orb, type in a coloured pill, and rarity in a diamond and in a thread inside the outline.
Power in a blue pill and Life in a red pill; the card text is centred.
Changed
The enlarged card has the same look.
Without illustrations (Collection, Deck Builder), the card's sigil takes the place of the art, in the card's colour.
Keywords appear in a column on the left, below the name.
Cards are lighter: the battle draws about a quarter less each frame.
0.14.0
New
New card look, “Arcane Glass”: dark glass with an outline and glow in the card's colour, cost in a hexagon and rarity in a diamond.
Card illustrations now show in full colour, in a framed window.
In card text, Power shows in blue and Mult in red.
Changed
Long names shrink to fit (no more “Revelation of...”).
At the bottom of the card, Power sits on the left and Life on the right; the enlarged card has the same look.
Lighter menu: the rune circle uses much less power and always sits centred on the title.
Fixed
Horizontal stripes on the illustrations of the enlarged card.
With “Reduce motion”, the rune circle appeared cut off at the top.
The Campaign could reopen on a locked book.
After a Quick Run, the button went back to the Campaign instead of Quick Run.
The shadow of the saved game buttons appeared cut off.
The font credits did not mention New Rocker.
0.13.2
Changed
New line on the main menu: “Forge your deck, throw your threats on the table and unleash an unstoppable cascade of damage.”
0.13.1
Changed
New main menu look: the title in golden letters, a rune circle spinning behind it, sparks in the five colours rising, and buttons with a golden frame and the map medallions.
New app icon and splash screen.
The main menu shows “Version 0.13.1” instead of “prototype”.
Fixed
The Campaign and Quick Run opened on the most advanced book; now they open on Book I and remember the book you picked.
0.13.0
New
Illustrated map: the act's path over a painted landscape, with your current choices shown large and what comes next in view.
659 illustrations: cards, portraits, relics, potions and scrolls, the map icons and the backgrounds for acts and weathers.
Battle: choose who blocks the counterattack, see the trigger order, arrows for what the enemy is about to do and charged blows a turn in advance; the total changes live as you drag a card; tap a keyword icon to have it explained.
Saving mana (the Reserve talent and the Mana Jar), perfect play (+3 gold), replaying the last attack and a warning when there are no plays left.
Card editions: Shiny (+Power), Holographic (+Mult) and Polychrome (×Mult).
Book IV of the campaign with 2 new decks (Gears and Endless Legion), unlocked with achievements, and 30 rare and mythic cards.
Potions and scrolls (up to 2), Elites with affixes, 6 new bosses, the Forge of Editions, Library and Vault on the map, relic sets, events with consequences later on and 6 new weathers.
Endless: a new curse every 4 antes.
Story: Book III, with the Nemesis, the rival Patrons and the ending. Challenges with 3 stars. A Land Arrival lesson and 10 new puzzles.
Nightmare difficulty (unlocked by winning on Hard), card mastery (Bronze, Silver and Gold), card backs for each colour completed in the Collection, a Profile in Statistics, and Planar Stakes in Quick Run and in Deck Builder decks.
Music: it swells during the attack, and each faction has its own theme in Book II of the Story.
3D enlarged card, mana curve in the deck and in the Deck Builder, hand card size, one-hand mode and confirmation for expensive purchases.
Changed
Battle with more feel: the enemy lunges, sparks on blocks, creatures crumbling to dust, mana crystals filling up and confetti or ashes at the end.
Statistics opens on the Profile.
Fixed
Losing or undoing in a puzzle no longer touches your saved game, and puzzles now have TRY AGAIN.
ATTACK could get stuck halfway through the Mulligan.
A replaced run can be recovered in Saved Games, and the notice “Saved to "Game N"” appears.
Cards with lots of Power and Life stretched the Collection and Deck Builder grids.
0.12.1
New
Hand cards with 2 taps: the 1st picks the card (it rises, with a golden outline and “PLAY”) and the 2nd plays it. You can also play it by dragging it up onto the board.
Holding and dragging a hand card moves it to another place; the card floats above your finger.
Settings (Game): “Playing a card” with 2 taps or 1 tap, and turning the Easy play TIP on or off.
Changed
Attack flames redone: smoother, with a hot core and sparks, and they follow the pills when they jump.
The boss entrance lasts long enough to read the name and the rule (3 to 7 s, even at 2×), with “Tap to continue”; it also appears at top speed.
Battle banners (ante, boss awakening, record…) no longer speed up with the game speed.
Fixed
Holding a hand card did not open it enlarged: the card rose under your finger and the touch was cancelled.
The attack flames looked broken (blocky).
0.12.0
New
New title screen: “We make Threats, not promises.”, a description of the game, an animated background and music.
NEW GAME asks for the mode; 6 save slots, each with a name you can change (Saved Games).
Quick Run (4 antes, any deck), Rematch and a history of your last 30 runs.
Flying, Trample and First Strike keywords, Land Arrival and 36 new cards (5 special Lands).
6 new enemies: Insatiable Glutton, Inquisitor of Silence, Illusionist of a Thousand Faces, Mana Leech, Living Wall and Iron Jailer.
Map: Treasure, Sanctuary (Blessings for the rest of the run) and Arena; 10 new events and 16 new relics.
Story: Book II: The Ten Factions (10 chapters). Plus 8 Challenges, 6 lessons and 10 puzzles.
Talent tree (18), deck levels with variants, Bestiary, Endless milestones and 32 new achievements.
Cosmetics: board mats, 5 new frames and final-blow effects.
In battle: ▶▶ speed, hand sorting, BEST ORDER, the play TIP on Easy and the library's odds.
Music on every screen, 21 new sounds, cinematic boss entrances, comets on the final blow and red edges when you take damage.
Per-card statistics, deck codes, CSV export and SHARE your run's result.
How to Play with an index and search; high contrast and performance mode.
Automatic progress backups and an error report you can copy.
Changed
Three weaker decks strengthened: Planar Convergence, Throne of Ruin and House of Debt.
Bosses no longer repeat in the same run.
Menu tidied into New Game, Saved Games, Learn and Train, and Collection.
The Deck Builder fits its columns to the screen; several notifications at once now wait in a queue.
Fixed
The campaign panel on the left disappeared when you changed book.
Scrolling in Achievements and other lists got stuck.
Buttons with long text were cut off.
0.11.0
New
Mage School (Game Modes): 6 short, playable lessons, one per mechanic.
One-line tips the first time each mechanic shows up (they can be turned off in Settings).
Talents (Collection): you earn points at the end of each run and buy permanent perks; they can be turned off and the points can be refunded.
Creature keywords: Vigilance, Life Bond and Protection.
3 new bosses: the Grimoire Thief, the Living Mirror and the Fog Witch.
Tapping the screen during the attack jumps straight to the total.
Replay the biggest hit of the run on the end screen.
2 new achievements: Mage's Pupil and Personal Grimoire.
Changed
Easier game: enemies have less life from ante 3 on, and on Easy you get 6 turns per battle (Hard goes up to 150% life).
Clearer card types: a coloured ribbon and an icon per type; Lands show a landscape, “+1” in place of the cost and “play: +1 mana”, and sit apart, at the end of the hand.
Enlarged cards explain Lands and keywords; the glossary includes the card types.
Cleaner card text: “Power” written in full and no abbreviations in brackets.
Fixed
Four cards had text that did not match their effect (they mentioned “Artefacts” instead of Relics).
0.10.0
New
Story (5 chapters, one per colour), 8 Challenges with medals and Training Mode.
Nemesis: a rival Patron who returns at antes 3, 5 and 7, stronger each time.
42 new cards: Tokens, tribes, Enchantments, Boost, Reaction and Mythics.
Colour Chains, sets of 3 seals, Vouchers in the shop and + cards at the Camp (Forge).
Unlocks through achievements, medals per deck, card backs and card frames.
Glossary on cards, battle history, run summary and a What's New screen.
Tabbed Settings: interface scale, compact mode, reduce motion, 30/60 FPS, keep screen on, optional warnings and progress export/import.
Changed
Battle with a fanned hand, relics in medallions, turn pills, portraits and scenery per act, sigils on cards and colour effects.
Simpler main menu: Continue / New Game, Game Modes and Collection, with a line explaining each option; difficulty moved to the campaign screen and to Settings.
Interface with fewer frames.
Some enemies have a shield or minions; the Puzzles were readjusted to the new rules.
Fixed
In English, two enemy actions (charging gold and destroying the strongest creature) appeared in Portuguese.
0.9.1
Fixed
0.9.0 could keep using the data downloaded for 0.8.0 (without boss relics, curses, poker formations and new text).
An interrupted content download no longer leaves mixed data.
0.9.0
New
Automatic updates: the game tells you when there is a new version and installs it over the old one, without losing your progress.
Planar Weather in each act.
Bosses that awaken at half life and talk, and 5 new bosses.
Spoils Chest, Contract Board and Court of the Gods.
Elite battles, poker formations and relics that grow.
5 new double-faced cards, a curse and 4 events.
Act interludes and colour-blind mode.
Changed
Enemy intent as icons, mana crystals, a heart for life and the attack breakdown when you tap the calculation.
A total that counts up, flames on the Power and Mult pills and a shake that matches the size of the hit.
Holographic shine on rare cards, new fonts and a compact relic bar.
Fixed
The relic bar pushed the screen.
Cards duplicated in hand for an instant, overlapping shop offers and card names stuck together.
0.8.0
New
Run map, “The Spark Chronicles”: 8 antes over 5 acts; in each one you choose the battle (Scout or Guard) and the stop (Shop, Event, Camp, Mana Spring, Profane Altar or Blind Merchant).
Planar Stakes 1 to 8 on each deck, unlocked one by one.
Mulligan on turn 1.
8 double-faced cards, which flip when you complete a mission.
Card seals in the shop: Fury, Wisdom, Corruption, Vitality and Tithe.
Recall: 21 spells that can be cast from the graveyard.
5 Patrons, who gain loyalty from cards of their colour and have three abilities.
5 legendary relics, only at the Blind Merchant.
Arena Draft and Mage's Puzzles modes.
7 new achievements.
Changed
The campaign's chapter groups are now called Books I to III.
0.7.0
New
Endless mode after ante 8.
Statistics and 18 achievements, with an on-screen notification.
Collection: cards, relics and enemies are revealed as you discover them.
Deck Builder (6 slots, 10 to 30 cards) to play in Free Mode.
Tutorial in the first battle.
Type icons, colours and rarity frames on cards.
Cards in English.
Dominant hand (action column on the other side) and large text on cards.
Content updates without reinstalling, with a digital signature.
0.6.0
New
Life carries over from battle to battle and is healed in the shop and at events.
Preview: how much each card adds to the attack, the expected damage, the LETHAL warning and the counterattack coming next.
UNDO the last play of the turn.
Drag creatures and relics to change the order.
Bosses at antes 4 and 8: the Judge of the Gag, the Toll Collector, the Keeper of the Weight and the final boss, The Zero-Sum.
6 new enemies, tied to the deck's act.
7 events with choices.
New shop: booster, new offers, relics by rarity, selling relics, healing, max life, upgrading and removing cards, and interest.
13 new relics (31 in total), with rarity.
Changed
Enemy life adjusted for the 5-relic limit.
Fixed
Enemies' two-line texts were cut down to one.
0.5.0
New
Settings: volume, language (automatic, Portuguese or English), animation speed, vibration and deleting your progress.
Pause menu in battle.
The run saves at the start of every turn and resumes exactly there.
Enlarged card with a long press; view the library, the graveyard and the deck in the shop.
App icon and splash screen.
English interface.
Fixed
Card names, enemy texts and the battle log that could not be seen.
The Android “back” button no longer closes the game: it opens the pause menu or closes the open window.
0.4.0
New
Main menu: New Game, Continue, Free Mode, Difficulty, How to Play and Quit.
Campaign with a story: each chapter is one of the 18 decks, with its own difficulty; reaching ante 4 unlocks the next chapter.
Free Mode, with every deck and without touching your progress.
Easy, Normal and Hard difficulty.
CONTINUE resumes the saved run.
How to Play and end-of-run screens.
Battle animations: drawing, cards flying onto the board, creature charges, floating numbers, particles and shakes.
Ante and turn banners and transitions between screens.
Fixed
The attack button could be hidden under the Android bar.
Channelling no longer uses the long press, which clashed with swiping the hand.
The screen no longer jumps between turns and long texts no longer spill off the card.
0.3.0
New
The 300 cards from the “Mana Cascade” design document, in 18 decks to choose from.
Channelling: swap a card in your hand for another one, 3 times per battle.
Spells count towards the turn's attack.
Formations by cost (pair, triad, curve, Arcane Storm and Prismatic Convergence), board position effects and retriggers.
Searching for and recovering cards, permanent growth between battles, and enemies that silence or take extra turns.
Multicolour cards and a deck selection screen.
Changed
Mana is now the turn + 1, without depending on lands; Lands give bonuses in hand and +1 mana when played.
The shop offers cards in the deck's colours, and multiplier relics got stronger.
Balance tuned by simulation across all decks.
0.2.0
New
The game is now called Zero-Sum.
Power × Mult cascade attack, step by step (creatures, formations and relics), with animations and a sound that rises in pitch.
New relics, formations and attack effects.
Changed
Landscape screen.
Creatures attack on the turn they enter, and only those that survive the hit can block.
5 turns per battle, hand refilled up to 5 cards, up to 5 creatures on the board and life restored in each battle.
Enemy life adjusted by simulation.
0.1.0
First playable version, still under the working title Arcana Run.
