Alley Cat

If there were an award for "most enduring gameplay per KB of data," Alley Cat would have won my vote. In what seems like an incredible feat of programming, Bill Williams was able to pack hours of fun and diverse gameplay into only 38KB of space. You start in a lively alley, with all sorts of objects flying out of people's windows, and a vicious dog hot on your trail. Your goal is to jump the fence into various people's windows, in order to fulfill various cat-like missions. One of the most amazing things about the game is that it actually sets its own clock speed so that the speed of your computer is irrelevant. This means you don't need Moslo to enjoy the game :)

Blockout

One of the best Tetris clones ever made. Blockout is essentially Tetris with a third dimension: depth. In this first official Tetris variant that was not published by Spectrum Holobyte, you must rotate the blocks in 3D in order to fit them on the bottom of the grid. Advanced users can play this game with odd three-dimensional pieces. A very fast and capable simulation, it solved the problem of hidden surfaces by displaying each block as a wireframe before dropping it down.
Blockout is also very configurable. You can rotate blocks forward and backward along the x, y, and z axis (although all you really need is the x and y axis), and you can specify how many levels deep or high/wide when you play. A seperate high score is kept for each configuration for fairness.

Manic Miner

Manic Miner and Jet Set Willy are without a doubt the two BEST games ever made for the Sinclair Spectrum computer. These incredibly addictive platform action/adventure games are grandaddies of today?s platform genre. Both games star Miner Willy, intrepid explorer who must explore 20 caverns in pursuit of treasures in Manic Miner, then clean up his own huge mansion (built from the fortunes he collected in those caverns) in Jet Set Willy. PC gamers now have a chance to try out these Spectrum classics for the first time, thanks to Andy Noble?s exceptional conversion of the Spectrum originals. If you wonder where platformers come from, look no further than these 1983/1984 classics.

Mind Shadow

Rampage

This is a side-scrolling action game for up to 3 players, in which you, mutated into a giant monster, have to trash one US city after the other. You can choose to be Ralph the Wolf, George the Big Ape, or Lizzie the Lizard. Playable, but not worth the name of the much superior arcade game. Although nothing like the original arcade version, you will find Rampage a fun game that's worth a few sittings, especially if you can find friends to play with.

Space War

In 1961, MIT received one of its first computers, the PDP-1 from the Digital Equipment Corporation. DEC and MIT administrators hoped professors and students would use the refrigerator-sized computer to solve the world's problems. Within a year, the PDP-1 was running Spacewar, the world's first videogame. Soon after, photon torpedos were being fired at opposing spaceships in research labs across the country.

Wheel of Fortune

This game nicely represents the TV show that we all know and love. Even to this day, Wheel of Fortune still is on the air and runs in the same fashion as this game does. You have the option for 3 people to play, or you can simple have the other 1 or 2 players as the computer. There are 3 rounds in total in which you have to guess letters to solve the phrase. Should you be successful at the end of the 3 rounds, and have the highest total of money, you will then advance to the bonus round upon which you can then win extra prizes. Upon starting the game, you have the chance to either start a new career or continue an existing one, which is useful if you've been doing quite well with a player in a previous game. Spin away!

Zaxxon

Zaxxon was originally available on the Commodore 64, Atari 2600 and Apple II (among others) in the style of an arcade shooter game. You are the commander of a airship and have to fight your way through each level, taking on enemies with your ammunition and dodging obstacles that get in your way - all while trying to keep an eye on your fuel so that it doesn't run out! Quite an addictive game. Runs best on new PCs using DOSBox if you don't have access to a very old, slow one.