review
Ok, besides the arguable claim of being the worlds hardest game, this game has a lot of basic design and implementation flaws. The choice to make the player a square put up against circles automatically makes your character feel clunky, and I saw you responded to another review claiming that the hittesting was "perfect" but that is a very ignorant claim, because it isn't, and I could show you plenty of instances in the game where it isn't. I'm not sure how you went about collision detection, but I'd be interested to see, just to figure out how some of the flaws I saw happening were happening... In fact just as an easy example, go to the level 7 and when it starts just move the box to the right out into the moving circles, it wont get hit. So the collision is not near perfect...I'd say it's not even good.
And then besides making the character a square, you made him much much slower than the enemies, which isn't that big a deal, other than causing frustration.
I think it would have been a very good investment of your time to figure out how to save the progress of the player in the game, because as it is with no saving if you don't have time to beat it in one sitting, you're discouraged to come back because of how time consuming and tedious the levels are. I want to beat it, but at the same time it's just tedious trial and error without any way of saving.
Another small detail are when you have the tips in between levels, since it's a keyboard oriented game, you should allow the player to pass the tip using the keyboard. Again not a big deal, just a small detail.
The checkpoints were a good idea, I was very disappointed to find out on one level that they only save once, that's a small detail also, but maybe make them disappear after you save on them, or make them save anytime you cross over them. What happened was I saved, got a coin, tried to save, and then died and thought I still had the coin... still a small detail...
Anyway those are all the bad things I noticed about the game, good things I guess would be level design... sometimes... and the simplicity of the game graphics wasn't bad either... Well I hope you take this as constructive criticism, and I hope it helps you in the future...