Currently there is no such mod existing for Unreal. What you may have seen on a TCP server is the WFlexMap mod which is capable of rotating up to 10000 maps, and instead of just rotating one after the other, it can pick maps depending on how many players are on the server the moment a map ends.
In order for this feature to work correctly, you have to give the mod additional information about each map, one "from" and one "to" value, e.g.
LargeMapList[123]=DmDeck16.unr 2 6
LargeMapList[124]=DmSinfonia 2 4
LargeMapList[125]=DmArcticCastle 8 32
would tell the mod to pick Deck for 2 up to 6 players, Sinfonia possibly for 2 up to 4 and DmArticCastle only for a real LOT of players (more than 8...)
If you leave out the extra information, the mod will assume "1 to 999" players (any playerload).
For the mod to pick on playerload, at least 2 players must play (picking a map for only 1 player makes no sense, so it will rotate also the very LARGE maps when no or only one player is on the server).
I have mapvote on my wishlist for UTeamFix 10, but you know the drill... time is a problem, and in this case, I don't know if I can make it at all... others have tried at it before me and failed
