If you're the type of person who likes a challenge, UnBlockMe from GzDev offers 7,800 levels of difficulty for the serious gamer. The objective, as with most really good games, is simple: get the red block out to the right side of the screen and into a gap in the wall.
UnBlockMe's interface and the mechanics of the game are really quite simple. Just drag the blocks up, down, and sideways to free up the red one. As expected, the game progressively becomes more difficult as you go up the levels, so stick with it if you think it's too easy at first. And, if you master the game in this mode, there is also an option to play the game based on efficiency, as in using the least number of moves to free the red block.
UnBlockMe is a simple game that can turn out to be really quite addicting. Don't say we didn't warn you. One minor issue with the application during the testing is that it placed a desktop icon without permission.