......
This really isn't too different from any other maze game I've seen on Newgrounds, but there ARE a few things you could do to improve this.
-Put in a menu screen, with the name of the game at the top, a "play" button below that, a "Newgrounds.com" button below THAT, and at the very bottom include a link to your profile. Also, a few previews of the game on the side wouldn't hurt.
-Instead of the square, maybe you could have flags that say "Start" and "Finish".
-Make it so that your mouse leaves a line behind it. Somehow, that's just plain awesome.
-Instead of sending the player back to Level 1 every time they die, have them be sent back to the level they were on. If you still want the game to be hard, then add a certain number of "lives". If a character dies but has a life left, sent them to the beginning of the level they were on. If not, send them to the beginning, or even add a "game over" screen that gives them two options: "Continue"(sends you back to Level1), or "Main Menu"(Sends you to the menu screen, IF you make it)
I'm not saying any of this will give you a frontpage, but it would probably be great for practicing your flash skills!