If you want a good challenge come check out Epik-Gaming's Epoch Server
(198.27.70.14:2332) version 1.0.4.2. Romaing AIs (Foot,Air,Driving) every now and then you will get a static message on your screen and anywhere from 2 to 4 AI's will come after you anywhere on the map and they will chase you unitl you or they are dead, several missions will well equiped AIs (loot thats found on missions includes armored humvees with M2 50 cal machine gun,MV-22 Osprees, MI-17 helis and a few fuel urals. This server also has free refuel and repair all you have to pay for is rearming your vehicle/heli. New AI city with a ton of high value loot IF you can make it through. No plot polls required for building alot of random spawn vehicles,evac chopper,walking dead, dedicated TS server, and the owners and admins are very mature and always trying to make the server better and are also very willing to help you if needed. Bring your friends/clan to the server and they will hook you up with free stuff. If you would like a change from PvP for a little while i really suggest giving this a try but beware the AI's are excellent shots lol