The game really is fun and challenging, a little unbalanced or unfair in some parts, but i really like what is going with this, i would only suggest some things that i think could help the game or at least try it.
1: capability of devouring the enemies, or at least some types, gaining more energy but with a cooling time and maybe a minigame to make it, like pressing a key repeatedly to break the enemy defence and devour it.
2: being able to devour the slime creatures to gain endurance, but loss movility, having to empy ourselves in contaiment cells.
And someting i think could be helpfull, is that we dont lose our weapons between levels, mostly because of the amount of enemies we start to face, and the lack of guns to actually face them, or at least, dont loose our ammo.
and i would really suggest that the levels don't obligate to loose the acumulated energy in big amounts, or at least, that the energy could be gained more easely, like getting a bigger amount from enemies and other sources.