Nice start
Good stuff first:
- It's tight -- no bugs that I could find.
- It's not impossible, but not easy.
- You've got the collision detection down pat.
Not so good stuff:
- I feel unrewarded: Yay, I moved a black square to a moving green dot over and over.
- Some sounds would have increased the interactivity, even a little *ding* when you hit the dot.
- Additional levels/goals would help, too. (i.e.: same game, but with a maze to navigate while dodging the red boxes and seeking out the One Dot).
In all, it shows that you have potential, so long as you don't let reviews like this one get you down. Keep plugging away.