I love this little game, though I have a bunch to say.
Firstly, some of the less good stuff. The fact that there's a lag between holding fire and firing is very unintuitive. If that's the point, and is a mechanic in the game, then that's cool. If not however, that's something that makes the game feel unresponsive.
Secondly thing is the constant jump. The jump should really only be triggered on keypress, or else if I'm holding space (because that means I'll jump higher of course (; ) I can end up jumping when I didn't want to.
Thirdly, if I press left and right together it goes right, instead of cancelling each other. Small thing, but something to look for when playtesting.
Fourthly, adding even some basic music or even just sound effects would make the game more impactful.
Lastly, I sort of forgot I can rearrange the keys until reading the comments here, so making some sort of in game reminder would be cool.
I know, it's only 48 hours, and for the time, this game is certainly great. All those nitpicks are certainly that, nitpicks. And that's because I absolutely love this game! The platforming is great. The jump feels very good, the speed and acceleration of the character feel great, the shooting is fun, despite the delay, and the fact that the bullets are kinda slow would make it interesting when adding moving enemies. I just wish we had a few more levels to play, but thanks for the level we got, and I hope to see you expand on this game some more in the future :)