STEAM RED FACTION + RED FACTION II FAQ
If Red Faction II gives you an error about putting the disc in your drive, simply REMOVE any discs currently in your CD-ROM drive. You should also UNMOUNT any virtual drives you may be using, through programs such as PowerISO, MagicDisc, etc.
Update 21 Mar 2010: If you in fact do not have any CD-ROM drive at all, some users have stated that using a virtual CD drive program and creating an empty drive can fix the problem. (PowerISO, MagicDisc, etc. Google is your friend)