I’m pretty new to Linux, and I’ve been looking around for games to play, and a lot of them seem like they’re mainly online. Are there any good free FPS or RPG games that have an offline mode with a good plot? I don’t really care much about graphics as long as they’re 3D.
have you tried googling " linux games "
or using Google/linux and search for games
games - Google Search
FPS – well use xbox or windows7 but there are some for linux but i do not play them .
Cube 2: Sauerbraten
fps - Google Search
42 of the Best Free Linux Games - LinuxLinks News Lists a lot of games.
You can also play most Windows games under WINE.
For a good free FPS with single player Warsow is worth trying.
As far as “offline” games go there aren’t many commercial quality games available that run natively in Linux. Neverwinter Nights and Prey can be bought fairly cheaply and there are Linux installers available for both. There’s also a demo for Prey available. After trying the demo I bought Prey on Ebay for just £3. An excellent game that Linux gamers should try.
How do you install Neverwinter Nights on openSUSE?
“Neverwinter Nights” no idea , never herd of it till now, the only install file i have found is from 2003
nwresources129.tar.gz
did you read the instructions in it
also from 2003 it might never work on 11.3
if you would post a link to what you want to install – then we might be able to help
Download the Linux Client Binaries and any necessary language files.
You’ll need to purchase the PC DVD to get a valid Neverwinter Nights CD-Key, but these can be got cheaply from Ebay and other online retailers.
There is another method using a Linux installer, if you are unable to download 1.12Gb.
It’s worth it, it’s a great game. 
Neverwinter Nights is one of the best RPG’s all time. Bioware provides a linux client and you can download the neverwinter nights content from the internet alongside with the client. You are still required a valid key from a retail version. You have also 2 expantions if you like the game and quite some popular servers online for all tastes and in many languages. Yes, it’s commercial, but it’s worth it. All recent hardware should be more than enough. Runs flawlessly on openSUSE 11.3 (GNOME/PulseAudio) with ATI proprietary drivers.
Be adviced that this is a real RPG! If you liked Baldur’s Gate or even Icewind Dale I/II, you will love Neverwinter Nights… if you are looking into something more in the scope of World of Warcraft, you might find it too boring.
Amén to that, brother.
The Penumbra / Amnesia games are good RPGs! Pretty graphics and creepy horror stuff too!
Nexuiz is a good game with decent single player