An excellent - and infuriating - Flash game, based on the radio-control adventures of Duncan Donaldo, who used to keep a highly-regarded weblog at seethru.co.uk. I don't know who developed the game itself - one of the seethru team, I guess. It's their copyright, certainly.
In this 2-dimesional, sideways-scrolling game, you control a helicopter, which you must guide through what appears to be a randomly generated underground tunnel, which is liberally festooned with floating rectangles. Holding down the left mouse button makes the chopper go up, and releasing it let the chopper fall. You have no control over anything else. The object of the game is to last for as long as possible. 1000 is a good score; Donaldo claims a personal best of 2148.
This game is wonderful - simple, addictive, well conceived and executed. As with all the best games - Tetris, chess, fighting - it is easy to learn, it takes a short time to get quite good at it, and a long time to get very good at it. There is no barrier between the player and the game - the controls work perfectly and are intutitive and direct, the collision detection and everything is spot on, and it only takes a click to start again once you've crashed.