About This Demo

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.

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.

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.

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. Negatives force you to rethink. You can't outrun fast enemies. Don't just shoot, solve.

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 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.

Create Combo Chains for Perfect Waves and crazy multipliers

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.

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.

Bosses That Would Make Mathematicians Sweat

Each boss is built around a mathematical concept that wants you dead (3 out of 9 bosses await you in the demo):

The Sigma Snake

• a colossal snake composed of numerical segments. To defeat a segment, you must deplete its value to exactly zero; fail to do so and the segment breaks away to hunt you down, adding their remaining values to its head. Once the body is gone, the head detaches and pursues you with a power level equal to the accumulated sum of every mistake you made.

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 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.