For information on how to set up a server, see this thread: viewtopic.php?f=117&t=71916
Find your [uDKGame.ini] located in your [Config] folder. (e.g. C:\Program Files (x86)\Renegade X\UDKGame\Config\UDKGame.ini)
Find the [uTGame.UTGame] section:
[uTGame.UTGame]
BotRatio=+1.0
GoalScore=25
bTournament=false
bPlayersMustBeReady=false
NetWait=15
ClientProcessingTimeout=30
RestartWait=30
MinNetPlayers=1
bWaitForNetPlayers=true
LateEntryLives=1
TimeLimit=20
GameDifficulty=+5.0
EndTimeDelay=4.0
GameSpecificMapCycles=(GameClassName="Rx_Game",Maps=("CNC-Field","CNC-Walls_Flying","CNC-GoldRush","CNC-Whiteout","CNC-Islands","CNC-LakeSide","CNC-Mesa_ii"))
bLogGameplayEvents=false
We're going to edit the GameSpecificMapCycles key, and more specifically the Maps subkey which contains all the maps in the current rotation.
To remove a map from the rotation, simply remove the entry from the map collection. To (re-)add a map to the rotation, add the map to the maps collection.