Road Blocks
Road Blocks is a small Flash game that starts off so easy you figure it's just a pointless exercise knocked out by it's author on the way to a real game being built. That's just the hook. Three minutes later you're struggling to see moves ahead, like in a chess game, but by then it's too late, you're into it. Kiss productivity goodbye for the day, cube monkeys.
Road Blocks [The Flash Games.com]