Had low expectations, but was disappointed by an actually enjoyable game. Given that it's just a demo, it's a pretty nice thingy :D
Also, these achievements would work well with the NG medal system. I've managed to get all of them besides the one on the far left; is it something secret? :P

cool game

Maybe make jumps on the first level a little less, "need to time this just right". That's more of a later level kind of "after they've gotten familiar with the game physics" kind of upgrade difficulty trick.