Doom is a 1993 computer game by id Software which is a lamdmark in the first-person shooter genre. It is widely recognized for its pioneering use of immersive 3D graphics, networked multiplayer gaming on the PC platform, and support for custom expansions. It single-handedly revolutionized the gaming industry. I am not much of a gamer, played only 15 minutes of Doom before. Nevertheless I couldn't resist the opportunity to play Doom on Linux and frankly it was a very pleasant experience, even though I suffered from some dizziness from the rapid movement. I survived in my first attempt today till I met the devil guys at the very end. Surely I will have better luck next time :)
Update: Yeah, I skinned em pretty good, several time in fact.

It was really fun playing the old classic Doom on Linux. Not only that you can also play Heretic, Hexen and Strife too. All for free obviously. Just follow the one line instruction below for playing these classics.

All you have to do is install vavoom (as root) from Fedora extras package:
yum --enablerepo=extras install vavoom

Vavoom is an enhanced open-source port of Doom. Allowing you to play not only
the classic 3D first-person shooter Doom, but also the Doom derived classics
Heretic, Hexen and Strife. Compared to the original games it adds extra
features such as translucency and freelook support and ofcourse the capability
to play these classics under Linux.

Enjoy!