Addicting, but there seems to be a bug
"Oh, this game is good, but there should be a map somewhere..." (finds the M button after collecting about half of the gems) "...oh, ok... this should be documented somewhere, a tutorial or instructions or something..." (reads the game description) "...ok, so I'm just stupid".
This game deserves a photo on the wikipedia article for "Awesomeness", but there's an annoying bug (?) already described by Omrikon: tiles begin changing when you collect some gems, and end up flickering in a very annoying way when you have 24 (this distracts you and makes some precision movements specially complicated). When you collect the 27th gem, the game suddenly becomes a COMPLETE PIECE OF CRAP that looks like ol' QBasic Nibbles (but the movements are still smooth and the jumping sound is neat). The same goes for the music: it distorts, like if it were being played on a cassette tape with not much battery, and sometimes a buzz is heard instead. (I've never seen a flash doing that, so maybe this effect was intended for some reason I don't understand).
Maybe this is because the 27 gems switching colors on the map/menu takes a lot of graphics resources that are grabbed from the rest of the game, even if they aren't rendered while the map is hidden.
My review is 9 because of this bug, it would be 12 or so if it were fixed and Newgrounds allowed it. On the other hand, maybe it's my fault for not having much memory, or something like that.