If Pac Man and Space Invaders are too graphically advanced for your retro tastes, this might be the solution; Lost Pig is a hilarious text only adventure (or interactive fiction) game. This might not sound interesting, but for people who have enjoyed games like 'Phoenix Wright: Ace Attorney' or 'Hotel Dusk Room 215', you might like this too.
The game requires two downloads, the Lost Pig file and its interpreter, Gargoyle. It's a very lightweight program, and won't eat lots of memory.Your job is to help a dimwitted Orc named Grunk to find a lost pig. You do this by writing commands into the Gargoyle interface, in which you read the story. It's a very simple program, though if you've never played a game like this, it can seem daunting if you have no idea what to write. Luckily, if you type 'HELP', the game will point you in the right direction, and you'll get a feel for it after a while.
If you enjoy reading, Lost Pig is a lovely way to spend some time, as your narrator, Grunk, is charmingly slow and very well written. It is ideal for a change of gaming pace. It is not, however, for everyone. The total lack of graphics might be off putting, and while the game has an inbuilt help section, it is hardly intuitive by today's standards.
Lost Pig is a real 'love it or hate it' game, but if you persevere, you're guaranteed a funny and unforgettable experience.