Nice game to start off... Here are my 2 cents:
The controls seems quite sensitive. The character basically zaps across the screen with quite a speed, so you often slip up a lot. This contrasts with the jumping, where there is no air control at all. These two elements makes the platforming harder than necessary.
I liked the idea of creating platforms, and having to choose between progressing and fighting enemies. I also see that you placed some secrets, which is fun.
By the way, it is possible to go out of bounds in 2nd map (Just go up ;) )... and you cannot reset (No such control listed??) meaning you need refresh the page & start from scratch...
Anyways. Thanks for sharing, and congradulations on your first game!