I'm totally overwhelmed - they come in swarms, like zombies! Honestly, the concept is quite cool, and it's been a while I finally get my hands back on the original doom POV. I myself can hardly find a good way to intertwine math with doom - one requires precision, the other is complete chaos. Well, now I see ;)) 

The only problem I found myself in is the fact that after you get killed you get back to main menu. It's more unintuitive to do so than to, let's say, give the player a health bar, and when they die they get a losing screen or something like that. That's it for my feedback. Keep up the good work man!

This quickly becomes overwhelming -which i think is fitting for this concept -trying to hunt and peck the right numbers as more swarm is pretty fun!!  This was an awesome use of the theme -nice work!! :D

I really like the idea of math doom, but it's a bit strange. Trying to create certain numbers by shooting certain numbers/symbols is hindered by the fact I need to shoot other numbers or risk dying. Actually having health might help though. The lack of a death or game-over screen is also very jarring since it just takes you to the menu if you die. The chain gun is also kind of loud.

Add & Subtract, awesome game btw

The mouse sensitivity is kinda too much.... But the gameplay is good. Love Doom!!!