I like how fast the game is, it forces the player not to waste too much time thinking. I tried the harder difficulty first, I wasn't able to finish the first floor. Then I tried the easier difficulty and already gave the first floor without problems. The hardest part of the game for me is shooting flying objects, I always die then. Music OK, graphics OK, fluidity great. Unlocking buffs is an excellent feature.
I can't think of how the game could be further expanded. A dedicated linux server would be great for mass expansion of the game (if the game offered multiplayer). I regret the absence of cooperative multiplayer. This would make the game much better.