Wiki only mentions that for Serious Sam 2, it mentions nothing specifc for th epreceding First encounter and Second Encounter. (only listing Linux unser supported platforms) Those first 2 are my favorites anyway.
It looks liek the first 2 are beta as well, but I didn't see that much in my quick search. It seems like they released the port for download. (the core and installation program, but still requiring the original discs/immages for data -like Xbox games on the 360-the games aren't freeware of course)
Edit: OK, yeah, both are beta and free to download but requiring the original discs/immages for the windoes versions, I'm not sure if the source is available though.
http://files.seriouszone.com/catdisplay.php?catid=76 "The linux ports by Ryan 'Icculus' Gordon formerly of Loki Entertainment"
and: http://wiki.linuxquestions.org/wiki/Serious_Sam
Quote:
Serious Sam is a fast paced first person shooter by Croteam, emphasizing intense action over tactics and strategy.
There is not a whole lot of support, but Icculus has done ports for both the first and second encounters. These ports require the original game cd.
There is a bug in the linux client for both versions that in some places can only be worked around with fly mode: open the console window by pressing ~ and then type "please fly" to activate it.

