Recommend me a good game that doesn't cost anything or need a friggin' registration.

Abandonia - Home of Abandonware DOS Games

Have fun.

Seek and Dread Online- 1.2mbs, online internet game and almost no lag!
http://seekanddread.de/
Note: It's aiming system is rooted :P

Go to www.byond.com. It has an extremely small download, the games are even smaller, and it has tutorials to make your own games. The game servers are small though.