Zero Sum

About the Game

You failed math class. Math didn't forget.

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.

That was the easy part.

Your Arsenal Is Unconventional

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 is a powerful grenade that can nuke even the biggest numbers if played right.

Multiplication? A slow trap. An AoE effect that slows everything it touches. Useful if you're smart enough to set up a kill with it. And then there's Sigma, a vortex grenade that sucks in every nearby enemy and combines them into a single number whose value is the sum of everything it ate. 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.

Die. Learn. Multiply.

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.

You didn't only get good at math. You got good at violence, too.

The Numbers Fight Back

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

Bosses That Would Make Mathematicians Sweat

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

• an inconspicuous boss that launches factorial projectiles. 9! splits mid-air into 9 × 8 × 7 × 6 × …, each number racing toward its anchor to recombine into something enormous. Kill the pieces before they merge or face their giant product.

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. Trapped in its grid, you must identify and destroy the composites and avoid the prime traps. Hit the wrong number and it breaks free as a real enemy. Clear the web to expose a leg joint. Fail, and the entire web turns into a swarm.

Sketched by Hand, Animated Like a Fever Dream

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.

Features

• 7 operator weapons with 22 firing modes total: every operator unlocks three to four distinct modes that change projectile behavior, AoE and mathematical consequences

• 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

• 6 game modes across escalating waves: Classic, Holdout, Survival, Conveyor, Boss Rush and more

• Roguelite progression: permanent upgrades between runs, temporary buffs within them. Every death makes the next run meaner

• 3 difficulty modes that not only scale enemies and rewards, but also introduce complete new boss mechanics

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

• A skill ceiling made of mental math. The fastest players aren't the ones with the best reflexes, they're the ones who can factor 391 in their head while dodging the swarm