CTFS is based on the same concept than CTF, except it's played with rounds. Each round, a team has to defend his flag and the other has to steal the flag and to bring it back in his base.
There are no items/health/armor in CTFS, when you spawn you are 100/150 and full weapon.
By the way, most of the time, Lightning gun and Railgun are disabled while BFG is enabled. To perform this change, use these commands :
/cv item -lg /cv item -rg /cv item +bfg
Selfdamage can be disabled, the game is faster when you can rocket jump whenever you want.
/cv selfdamage false
Likewise, you can just callvote a special submode of CTFS, which is CTFSPUB. It has the previous changes.
/cv mode CTFSPUB
Like in CTF, there are two kind of scores. Player score is the same than CTF, but team score is different given that the game conditions are completely differents.
Basically, score limit is set to 15 and the game is played with 6 players.
The most played maps are :