Some of the levels seem haphazardly placed, and I could beat several of them by just cheesing them. 10 really good levels would have been better than 20 levels. 18 and 19 were really good levels, and level 15 was the first time I felt challenged. level 20 was easily cheesed. Otherwise, the design is really simple, and it is clear what to do. The use of theme is ok, but it isn't exactly time-travel. It feels more like I'm just placing a copy of myself before I respawn. I like the bright colors, and the sounds are cool, but they get annoying without a pause button.