First game ever? That’s impressive! I wish my first game was this coherent :D

You’re spot-on, on three key points:

• Saving high score.
• Making assets yourself.
• Reasonable download size. It’s amazing how many seasoned game devs still mess up all three of those.

A few ways this one could be improved, you might keep in mind for next time:

• Needs more opportunity for expression from the player. Maybe cut the jump off when we release space bar? Maybe allow left/right arrows to move a little horizontally?
• Difficulty should increase over time. That means either speeding up, or decreasing the max distance between hazards, or both.
• Powerups shouldn’t be reachable without jumping, and hazards should kill you faster. Rule of thumb in this kind of game: If the player lets go of the keyboard and just lets it run, he should be dead in a couple seconds. (I let go after 20k points and it ran for at least a minute before ending).

But I really am impressed with what you have here. If I win a prize this jam, I’ll give it to the MJFF in honor of this game.