Code a Multi-User-Dungeon game that runs in the command line and allows people to connect to the server that you will code without having the client. That is, they can simply telnet into your MUD server, register or log in, and play with others in real time. The game environment should of course be textual, meaning that everything is described rather then drawn. The game should have a simple map, with at least 30 rooms. Each room has exits to other rooms. Some rooms should have monsters and NPCs with whom you can trade items or get quests. The game should have at least 10 quests to start with. Players can "see" other players in the room by looking at the description of the room. They can chat with each other, trade and also kill each other.
Anyway, be creative.
Note: once you make the MUD server, consider building a custom client for it to make it easier and more fun to use.
And by the way, linux doesn't have any decent MUD client. You could even start an open source project. Look at windows MUSHclient to get the idea of the required standards.
