Petri Purho is the master of the fast-developed little indie game with just a little bit new to say, and Planet of the Jellies is a good example. The gameplay is basically a cross between a "falling blocks" game (of which Tetris is the canonical but by no means the only example) and the "match three" game.
Little aliens dance back and forth across the screen top, Space Invaders style (but in a Dean Martin-cool sort of way, with brightly colored two-stage animations and a lounge music score), but they don't drop bombs. Instead, you can click on one to have it drop to the ground, Tetris style, and if you get three adjoining, they disappear and score you points. It's non-trivial to plan your drops, what with the shifting alien ranks, and the game is lost when an alien reaches the ground--or more likely, intersects with the top of one of the piles you've built on the ground and haven't managed to get rid of yet.
So there's a little bit of gameplay innovation here, at least in the crossbreeding of ideas from two different genres; but the whole is more than the sum, because the nature of the animations together with the style of the music produce a feeling of delightful cool, sort of the 80s arcade meets the 50s Brat Pack.