If you're really 11, this is very good work! There are quite a few problems:
- Falling into a sand pit without being able to go back to checkpoint is a big one (didn't happen to me, saw it on the stream).
- Also, after pressing the switch, the doorway didn't open fully, so I couldn't get through and had to stop there.
- The weapon's movement was strange, so I wasn't sure when exactly I was attacking, it seemed like it happened about a second after I pressed the attack button.
Those are the three biggest problems I saw. There are also tons of tiny decision things you could do to improve your game, but you'll likely learn them if you just keep making games. Good luck on your future projects!