© 2026

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

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.

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: 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
• Different game modes with a wave structure: Classic, Holdout, Survival, Conveyor, Boss Rush and more
• Custom Runs, where you can design your own game mode to your liking or math knowledge
• 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.