Yes I know you've played Asteroids. Heck I bet you've even played Asteroids Deluxe. Who cares? It's worth playing again. It takes all of thirty seconds to figure out and the replay value is through the roof if you even remotely enjoy the concept of playing games for score.
By now we all know what Asteroids is about. There's a field, a ship that turns in either direction and uses thrusters to get around, asteroids that break into pieces, and those damn UFOs. Deluxe mixes things up a bit by providing the player with a shield that can take a few hits instead of the wholly unreliable hyper-speed as well as adding an asteroid that behaves more like a cluster of homing missiles that follow the player.
Where Deluxe really shines is in how it redesigns certain aspects. The UFOs will typically focus on either the asteroids or the player. This can work in a number of ways since the rocks are just as much of a threat to UFOs as they are to the player and at the same time they can create chaos as the player is trying to focus on something else. Asteroids has never been the kind of game where one can just blindly fire away at everything and expect to survive. In fact it's easy to get overwhelmed if someone allows the screen to be filled with tiny rocks. Survival is tied to asteroid-management and even when the player can contend with that the wild-card that is the UFO can ruin everything very quickly.
This depth is what helps Deluxe remain a classic for all these years and its excellent controls make it playable even today.