As I recall my father's last words
As I dismounted my camel
That's when it all started.
Spelunky is a free indie game that takes the random level generation, permanent death and complex item interactions found in games like Nethack and applies them to a 2D platformer. The result is brilliant, addictive, and mind-breakingly hard.
You control a character with a distinct resemblance to a certain archeologist, trying to get to the end of a series of randomly generated levels, killing enemies, collecting treasure and saving damsels in distress. Your character can jump, use his whip and carry a single item, such as rocks or guns, and use ropes or bombs to climb or blast his way through levels. What makes the game really interesting is the interactions of the various items you can find. At it's simplest, this can include things like picking up and throwing nearby rocks to kill enemies, but it rapidly becomes more complex: after a few deaths, I was stealing from shopkeepers, triggering boulder traps to demolish walls and trying to juggle the damsel in distress, a shotgun and a golden idol.
Make no mistake: Spelunky is hard. So far I have died more than fifty times, and I've only just made it into the second area. I died more than ten times in the tutorial. As in Nethack, death is permanent: there are no saves, extra lives or continues. The random level design can result in some horrible obstacles, but never seems to be unfair: there's always a route through a level. As most deaths are due to your own stupidity, this means there's a constant impulse to have "just one more go".
Spelunky is made by Derek Yu, and can be downloaded from http://www.derekyu.com/.