It is a good work not my favorite, but still a good game! Well done!

The controls are responsive enough, and the enjoyment I got out of it was decent, if only the background was not plain. Anyway keep it up, and will we be seeing Jack the Jumper 2?

A for effort! Your on to something, the music is catchy and the collision detection is good! Add some enemies (Not sure didn't get past the hard jumps on level two!!) and this isn't too bad! Good job.

Good job, nothing really new there, but still a game I can enjoy playing :)

By the way, I think I found a bug with the jump sound effect...
When you are in the air, after jumping, if you press the up key again, the jump sound effect will play. Also, if you decide to hold the up key, this will make you jump once, and when you reach the ground you jump again, that's fine, it's just that the sound effect will only play on the first jump if you hold the up key.
Which I don't think you really want that, I think the game will be better polished if you fix that :)

But in general, great work :)