This game is very nice, easy to play, and easy to understand… But it is somewhat broken
I noticed a few glitches in the game I would like to mention to you.
First, you can actually mass collide, or something of that sort, through some walls in the game. When you get to stage three, you can easily go through the wall and possibly fall through the floor next to the button on the wall. I noticed that immediate, especially when I went to go push the button, seeing as I went through the wall completely.
Second, when you get bombs, you can make it so you can place more then 1 bomb. every time you touch the ‘black box’ for the bombs, you get the ability to place another bomb. More than one bomb can cause you to go through the floor. I got it to the point where I made about 6 or 7 bombs, and then it just blew me through the floor into limbo, making me restart the game.
Since I had to restart, I didn’t check anything past that point.
I have a small suggestion though. You should try to make it so that you can jump upwards off of walls, so that you can go up vertical pathways by jumping off of each wall and bouncing up. It would give many more possibilities to a game like this 
Also, I suggest that you make your levels a bit more interactive. Everything seems a bit too still. You should try adding some small sound clips for when you set off a bomb or have a large brick fall (or something like that), or for even when you collect the stars. On the suggestion of movement, I suggest you try adding some moving objects. For example, you should try adding some water or trees that have a wind effect on them somewhere. These objects can be in the background, it doesn’t really matter if they are interactive or not. Just so that theres more movement, it’d be better. (please note that this is just my opinion, by no means do you have to do any of this
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The game didn’t seem to lag at all. I used the flash version of the game when testing this. The only other problem I noticed is that when you have your cube collide with a wall, it will sometimes make your cube move back and forth really quickly.