This game is cool. Made a lot more epic when Opera rendered the background as transparent. This was a neat effect and I feel bad for everyone that can not see that.

Some textures would be nice.
Maybe a tutorial?
the second level took forever to get up the final platform.
I like it still so 4/5 for this. Good job.

It was pretty fun. I suggest losing WASD and using A for jump and S for shoot. Using the mouse doesn't make sense, and using shift is uncomfortable.

Cool game, though. More sounds and lighting would be nice.

This is a pretty good game. I like overall simplicity and gameplay. Completed the game :)
It is good to see that challenges are introduced one-by-one, keeping the game interesting.
Things that could be changed:
» Weapon shooting sound. It's a bit annoying. It would be also nice if sounds were '3d', meaning that volume and position should depend on distance to character.
» There could be another level after the first with red capsules\enemies. Second level with these was the one that I crashed a lot at (mostly because of trying to complete it without killing anybody and that gap without chance to jump out of it).
» Colors of levels could be different (if you are going to keep the game in simplistic style). That would add some variation.
Overall, keep up the good work.

Good for your first game, but it could use a few things.
-Lighting
-Better Controls (Arrow keys and Z/X should be optional)
-More level design/Variety (Simple platforming gets old fast)