From Quake Wiki
This should be a one-page quick-start guide to getting, installing, and actually running the game, with links to other pages with further information.
Where to buy Quake
Apart from rummaging your favourite market of used goods (flea market, friends, random online communities) you can get Quake at:
Amazon (don't forget to check your local branch)
Ebay (don't forget to check your local branch)
Steam (Warning: It does not include the excellent soundtrack, you would be missing a lot)
Be careful that you do not accidentally buy a shareware disc (the soundtrack is on it, so at least you got something for your money).
- shareware version
- windows, dos
- mac/linux -- get a port!
- basic batch file/shortcut with some standard command line stuff
- system requirements/video card weirdness