We don't know who Greg Roberts is, but he's certainly one unlucky guys if he's all alone against a bunch of underwater assassins. In this case, the entire world is at stake, as aliens from beneath the world's oceans rise up in an attempt to subjugate all of earth.

At least, that's the basic premise behind MicroProse's X-COM: Terror from the Deep. It's a strategy game that forces you to take on the hordes beneath the world's oceans to defend human life. While it isn't its well-remembered older brother, X-COM: UFO Defense, it's still a good game from the 20th century.

Don't worry. It's not that archaic. It's just that Valve's Steam content delivery service has opened up X-COM: Terror from the Deep for another round of play with a "Retro" tagline. Until May 11, Steam users can pick up their own copy of the game for a discounted price of US$ 2.45. After that, you'll have to shell out US$ 4.95 to get it. Why not give underwater alien-busting a go, eh?