Jirosum is a 2D horizontal shooter themed around the use of mathematics to inflict damage on enemies. How it works is that you can absorb enemies with different numeric values up to a set limit, then fire a projectile that deducts the health of every enemy it touches until the number depletes to zero. You might want to be careful not to accumulate too many points, as any leftover value will turn into negative energy and starts to chase after you.
The fox's ability to absorb numbers increments by five for every five hundred points acquired. The game ends roughly after you've improved your special move twice, and there are no boss fights in this competition release build to speak of. Instead of some reward or an animated cutscene, the game just unceremoniously dumps you back to the desktop without so much as a congratulatory message to indicate that you've mastered the ways of the calculus.