M.U.L.E. was originally released in 1983 for the Atari 400/800 and was later ported to the C64 and the PC Jr. While critically acclaimed, it was not a commercial success. It is remembered, though, long after better-selling games of that era have been forgotten, and today recognized as being far ahead of its time conceptually. Now, it is playable online as Planet M.U.L.E. (free), with an interface only slightly cleaned up from its earlier incarnation.
In M.U.L.E., you control one of four colonists seeking to develop the planet Irata. Other players control the other three characters. You build mines, farms, and solar plants, and buy low and sell high in order to raise the income you need to keep developing. Random events from meteor showers to equipment breakdowns liven things up. (M.U.L.E., by the way, means "Multiple Use Labor Element".)
Planet M.U.L.E. is a faithful reproduction of the original, and keeps the original's focus on multiplayer play. Those looking to "pwn some n00bs" might want to look elsewhere--first, the game has no means of directly attacking other players. Second, although it is a very competitive game, the only way to truly win is if the colony achieves its goals, which requires all four players to cooperate to some degree. Can you manage to work with your opponents and still come out on top? An itchy trigger finger (mostly) won't help you here.
I say "mostly" because there are some time sensitive components. Selecting plots of land requires a fast hand on the space bar. (Oh, yes, you use keyboard controls, just like Grampa used to.) You have only 45 seconds to complete your actions each turn, and even that assumes you have enough food. Too little food, and the timer bar shrinks to nothing. It's not possible for one player to easily achieve self-sufficiency, so trade--conducted through a dynamic auction system--is essential. Gameplay can be a bit slow-paced, as Planet M.U.L.E. models the multiplayer mode of the original, which required players to swap seats at a single computer as their turn comes up. Between each player's moves, the auctions, and other events, a full turn of the game can easily take 4-5 minutes, and games are 12 turns long. Players used to adrenaline pounding action with explosions may not find this to their taste.
Planet M.U.L.E.'s underlying economic and production models are simple compared to, say, Civilization IV, but much like chess, they provide a lot of strategic choices and there are few uniform paths to victory.
Unlike in the days of yore, you do not need to swap seats to play--you find opponents online. You can have some of your opponents be AI players, but only for practice games. If you want your name on the Leaderboards, you have to take on real live people.
The game is free to download and play, though an Internet connection is required, and you may have to set up port forwarding on your router. If you like economic and production games, fondly remember M.U.L.E. from the early Eighties, or have just read about this game in "Best of..." and "Greatest ever..." articles, download it and check it out.