I play Second Life (Linden Labs) sometimes on mine its not very action packed but interaction with real people and unlimited avatar customization among other things beats the hell out of The SIMS if you know what you are doing.
How old can they be? Homeworld 2 was good. Total Annihilation was my favorite RTS. Command and Conquer Generals was also fun. If you don't have a comp that can run Classic/OS9 to run TA, TA Spring is a cool project.