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.
This is a screenshot of B2B_Prison made by Drimp, it shows abit of the outdoor area of the map
Like I said in a previous comment the ground is to flat, you will hardly ever find a place that has perfectly flat ground. Just create some small displacements to put on it and it will look alot better
From the angle of the screenshot you can't see most bumps in the ground but in game it does look realistic.