Yes you can play offline ^^
3 choices are possibles to do your pwserver:
1. Using coLinux, maximum players capacity of 45.. and it's so long and hard to do.. but you don't need a lot of ram like vmware x)
2. VMware and beastie image, it's more easier than coLinux and you have more players capacity. But you will need a lot of ram if you want to open all instances and world !
3. Linux dedicated computer, the best and more stable way to do a good pwserver! =) But you will need a second computer.. 1 for the server and 1 to play ^^. It's a nice way if you want to do a small pwserver for you and your friends =) For small friendly LAN party too ^^
Good luck!
tt1:
Romulan.