I had to share this one because it's an example of an amazing game built on an extremely simple concept: chain reactions. I don't know if there are many games like it out there, but it's my first experience with such a game, and I was completely sucked in. Do not click here unless you're prepared to give up the next 1.5 hours. It's crazy fun.

Played it when it was released a while back, got bored since the game goes from some strategy to almost none. If I remember correctly you just clear you points and put them into the shape of the level and win every time. Then it goes from that strategy to randomness and hoping something happens.

This reminds me of Every Extend.