So, you read the description and played the game for a bit. The mechanic seems pretty obvious: when you refresh, your previous avater remains in the level (but uncontrollable). Then you reach level 7, what a stupid game you think.
You proceed to read the comments for an explaination. Only hint being: "when you leave the this page, you lose control of your avatar". Ok, so I just press F5 and then hit cancel? Nope. Then it hits you, because you're a genius (or you're good at reading comprehension). What if instead of refreshing the page (leaving), I do that other option that I won't mention in order not to spoil the puzzle.
Ladies and gentlemen, though it looks like the art was made in paint and it is annoying that you have to play every level again when refreshing, it's a masterpiece.