Quake 2 is free software now
id Software has released source code of Quake 2 under GNU GPL few years ago. You just need to buy original game to get those datafiles. But some people are creating free datafiles to make it completely playable with them.
All your base are belong to us
Best feature in this emulator is, that it can run Sega Genesis-version of that game called "Zero Wing". All your base are belong to us.