Mosiaque is a very original puzzle game that I haven't quite figured out yet. It appeared on the App Store a little while ago from a company called Winning Blimp, and the core idea of the app is that you need to clear the screen of colored squares by firing them in from the sides.
The issue, however, is that if the square you shoot in hits a square of another color, it will switch out instead. Squares of the same color get cleared off, so your goal is to try and fire squares of the same color together, lining them up and clearing them off the board, refilling your meter for more shots. Mosiaque is the kind of game that's simple to play, but fairly tough to master -- even with the playtime I've put in, I'm not completely sure how deep the game's strategy gets. But there is a solid amount of fun to learning the game's mechanics, and as you play through the levels, there are some new tricks, too. Eventually, black blocks show up which will block your shots, and "void" blocks will appear that keep your shot meter from filling back up if not cleared right away.
Mosaique is a lot of fun, and it's very original, both in look and in gameplay. It's worth noting that there are no in-app purchases in this one either. Buy the game for US$0.99, and you'll have access to the game's unlimited parade of levels. That should be more than enough to get you figuring out exactly how it all works.