I'm the guy on the subway who is playing Collision Effect. I used to be the guy on the subway playing Drop 7. (Everyone else is playing Angry Birds.) Since I downloaded Collision Effect a couple of weeks ago, it has been my iPhone obsession.
All I'm doing in this game is tapping colored orbs that are floating through virtual outer-space. If I tap any green one that flies by, all the other greens fly toward it and the greens are eliminated. Same with tapping the reds to attract reds, the oranges to attract the oranges, all the way through the color wheel. The only way to fail is to have any colored orb collide with orbs of a different color. Within a minute, you will fail. , I've hit eight million points with this simple game and can't stop trying all over again. The game is as simple, brisk and addictive as my current iPhone favorite, Drop7 and as polished as Tilt To Live. I have no complaints.
The 99-cent Collision Effect is from development studio Vishindo and publisher Chillingo (they published Cut The Rope and those Angry Birds).
There's a lite version, so you can try it for free. Do it. [UPDATE: I erred; there isn't.] Possible iPhone Game of the Year, as far as I'm concerned.
Collision Effect [iTunes]