Zero Sum

Zero Sum is a pencil-on-paper twin-stick shooter roguelite. Your enemies are numbers and your weapon is math. No health bars. No hit points. Just raw arithmetic violence.

A "48" is charging at you. You fire ÷2. Now it's "24". Three more divisions: "12," "6," "3." Now switch to minus. Bang. Bang. Bang. Zero. Gone. Next.

Wishlist now! The numbers are counting on you not to.

Fight through different difficulties and game modes with a variety of arithmetic weapons. Face 9 different bosses based around mathematical concepts. Fine-tune your experience to your math knowledge level, from subtraction and addition, to division and multiplication, up to root and modulo.

Enemies aren't just walking health bars. A prime number can't be cleanly divided. A factorial grows exponentially if you ignore it. Negatives force you to rethink. You can't outrun fast enemies. Don't just shoot, solve.

Forget guns. You carry operators. Minus and Plus are your reliable sidearms. Precise but boring, until they save your life. Division rips through enemies. Root turns big numbers into rubble. Modulo nukes even the biggest numbers if played right. Multiplication? A slow trap that slows everything it touches. Useful if you're smart enough to set up a kill with it. And then there's Sigma, turn a massive swarm of numbers into one big, easy-to-handle target.

Seven operators. Twenty-two firing modes to unlock. Every shot requires a decision. Every clean kill and clever combo rewards bonus points. Integer split, perfect root, modulo blast. The game knows when you're showing off and rewards you for it.

Every kill can be a clean kill. Divide a number into a perfect split. Root a perfect square down. Land a modulo that leaves exactly zero. The game tracks your math and rewards precision.

Chain multiple clean kills for combo multipliers. Perfect wave? No misses? Bonus points. String together operations across different operators for Clean Combo Chains. The flashier the math, the better the reward.

Sloppy kills still work, but clean kills let you progress faster and score higher. In Zero Sum, showing off pays off.

Run one, you're rationing division ammo. Do you minus this 72 down shot by shot, or use your division for the perfect clean kill? Do you root the cluster of 16s for instant clears, or hold it for the tanky 256 barreling toward you?

Run twenty, your chain-divides ricochet through swarms, your root shotgun pulps clusters in a single shot and your Sigma vortex eats half the screen. Permanent upgrades carry between runs. Temporary buffs stack within them. Every death makes the next run meaner.

Standard Mode is the core roguelite loop. Chain smart math, build combos, aim for Perfect Waves, and fight through bosses. Die, learn, upgrade, repeat.

Verdict Mode is a precision test. Each enemy requires exactly one correct operation — ÷, √, or %. A clean solve removes the number instantly. A wrong answer triggers consequences defined by the challenge author. No second chances. No spray-and-pray.

Target Mode flips the script. Instead of reducing enemies to zero, you must transform each number into a specific target using +, × and Σ within a limited number of operations. A built-in reachability solver monitors every enemy in real time and flags impossible states on the spot, so if you're stuck, you know it's your math, not the puzzle.

Zero Sum includes a fully customizable in-game challenge editor. Design custom math puzzles with your own wave sequences, enemy spawns, operator loadouts, traps, and resolution rules. Built-in validation catches unsolvable configurations before you export.

Every problem set compresses into a compact share code. Copy it, paste it, send it to a friend, drop it in chat, post it online. Anyone can play your challenge, get graded on a Report Card and send their results back to you as a code.

Set your own grade thresholds, write your own teacher name, add custom per-grade comments. Build challenges for your friends, your community, your viewers or for a classroom. The tools don't care who's playing. They just grade.

Nine bosses, each built around a mathematical concept that wants you dead (a small selection):

The Euler Owl

• a wise creature, firing Taylor series bullets that duplicate. Deal with them before the expansion overwhelms you.

The Factorial Factory

• a stationary boss that launches factorial projectiles. 9! explodes into 9 × 8 × 7 × 6 × …, trying to recombine into their product. Reduce the pieces to zero before they merge.

The Pi Boss

• a pie protected by digits. Each slice of pi must be dealt with to turn armor into weak points.

The Yin-Yang Boss

• two spinning halves, one light, one dark. Focus too much on one half and the other goes berserk. Balance the harmony meter or get swarmed.

The Prime Sieve Spider

• an eight-legged boss whose web is the Sieve of Eratosthenes. Identify and destroy the composites while avoiding prime traps. Hit a prime and it breaks free to chase you. Clear the web to expose a leg joint. Fail, and the entire web turns into a swarm.

Zero Sum looks like your notebook came alive and got angry. Enemies are the doodles you drew when you were bored in math class. Except these doodles want revenge. Every menu is a school handout — quitting the game requires a permission slip.

• 7 operator weapons with 22 firing modes: every operator unlocks three to four distinct modes that change their behavior and your playstyle

• 80+ upgrade nodes across the operator tree: chain division, shotgun roots, area-of-effect modulo blasts, freeze lines, Sigma vortexes and more

• 9 boss fights built around real mathematical concepts: exponentials, prime sieves, pi, harmonic balance, factorials and more

• 3 game modes: Standard roguelite runs, Verdict precision challenges, and Target puzzle combat — each with unique operators, rules, and scoring

• Full challenge editor: design custom problem sets with wave sequences, operator loadouts, traps, and grading rules. Then share as compact codes and get graded on Report Cards

• Multiple arenas with different wave structures and layouts

• Roguelite progression: permanent upgrades between runs, temporary buffs within them.

• 3 difficulty modes for all knowledge levels with hard mode introducing additional boss mechanics

• Twin-stick controls with mouse + keyboard and full gamepad support

• A skill ceiling made of mental math.