If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Work through all 25 levels as fast as you can and submit your score to the leader boards.
Use the mouse to escape.
On each level you need to find your way to the exit (green portal) as quickly as possible.
Killing an enemy (red block) will give you a small (5 second) time bonus to your end of level score.