Steam has them as do other places I shall not discuss. Then you can find the other Doom games on the Internet.
If you have your pi connected to the same network as your PC you can find the doom script in the ports section of your roms folder. If not, you have a little more work to do. You can stop right here if all you want is the freeware version. This is the Doom emulator, and it comes with the freeware version of Doom. Settings > Manage packages > optional packagesįind prboom.