Fun:
Due to how the evolve mechanic works, you re encouraged to suicide against enemies you haven't seen before. Since you can carry multiple enemy abilities, there is no trade-off to dying aside from restarting the entire game level. A checkpoint system is absolutely required if suicide is encouraged. Without it the game felt tedious.
Aesthetics:
Seems new to pixel art. The ground tiles were passable, but everything else felt like beginner work.
My suggestion would be to follow a color palette for everything. Afterwards stick to an outline style, and clean up jaggies.
Music:
No music. Ambient background noise instead.
Sound:
The ambient background sound was nice, but the other sounds were clearly made in sfxr. These sounds should be avoided unless the game theme is 1970 arcade game feel. I suggest finding one of the many available free sound packs online for future projects.
Mechanics:
The movement felt sluggish. A slight movement speed increase might be beneficial.
Jumping and gravity felt good. Could use some polish but otherwise good.
The spike effect and boots were confusing. I thought spikes would kill on hit, and boots would let me fly. A tooltip explaining the new ability would be nice.
The aiming and shooting ability was well done. I expected to only be able to shoot horizontally. Once you get this ability, the other abilities feel completely useless, as I can kill all other enemies at range. It felt like a lot of time was spent implementing this. Perhaps scrap more time intensive mechanics next time and focus on what you already have.
Story:
None as far as I am aware.
Theme:
This idea was unique. I can see a lot of potential here. Needs better implementation, but otherwise top marks.
The evolve mechanic is the clear winner of this game.
Marketing:
This usually isn't included, but it is absolutely essential as a game dev. Getting people to play your game is not easy, and I wanted to praise you on your ability to market this. Rating other games, posting your link on the discord, and most importantly implementing webgl are great for getting your game known.
Anyone can make a game, but getting someone to play it is an altogether different challenge. Great job.