I first heard of it through a friend who claimed it was his absolute favorite game as a kid. Death Duel is pretty much insane. You play as this giant, upgradable robot and you duel to the death from a first person view on an alien desert, but there's a lot of strategy due to all the destroyable objects in between you, and your opponent that you can temporarily hide behind. You get 3 weapons at a time, which you can purchase at the store from this fucked-up cyborg dude and his monkey.
(CHECK OUT THAT CARNAGE!!!)
If you run out of health, ammo, or time - you lose. So you really have to develop a strategy to ensure that you continue on to the next challenger. Think Punch-Out, except with giant robots/monsters instead of puny humans, and missles/grenades/machine guns instead of boxing gloves.
Oh yeah, and then there's the 16 bit ring sluts who say catchy phrases like "Kick his asteroids!"
The action-packed game really has a top-notch sense of humor.
Here's a pretty good video review of the game from one of my favorite game critics if anyone is interested...
http://www.youtube.com/watch?v=G78tRzVw7so