On the red level you're supposed to kill specific enemies and backtrack to see new open parts of the level, sorry it wasn't clearer. The numbers on the bottom right are your ammo, and sorry for the dizzying head bobbing, thanks for the feedback!
Ok, finished the game! Maybe I just suck at FPS, but that HEAL cheat was a lifesaver. It would be nice to place checkpoints when you die bc restarting the level from the very beginning was kinda brutal. Running across the platforms with the speed cheat was loads of fun, although it was technically not necessary bc jumping off the platform towards your destination respawns you at your destination HAHA. Lastly, the floating eye enemies were kind of a pain bc at some point they floated high enough to become unshootable; it would be nice if they only went up to a point where the player can still shoot them. Overall, it was a really enjoyable game with cool aesthetic! Great work!