Base 2 Base is a Half-Life 2 Multiplayer Modification which puts 2 teams against each other (Red & Blue) and they have to fight to reach a teleport that is above the enemies base. When a player from that team goes through the teleport they are teleported to a safehouse where they can watch the battlefield on a monitor. First team to have all of their players through the teleport into the safehouse wins, and if a player is in the safehouse and wants to return to the battlefield they can do so by suiciding.
Well if you look through the screenshots of this map you can see how it has changed a lot. I have once again changed the lighting to fit in with the inside parts.