Unreal Development Kit (UDK) is an open platform utilizing UnrealEngine3. It offers limited example content - first-person action game. It features simulated 3D environment with a limited amount of different locations. Big advantage of UDK is that it features its own scripting language UnrealScript that is used to program the game mechanics. Everything except the 3D engine is open source and can be modified by the user. This makes the game easily modifiable. Also there is huge on-line community around this game providing us with new items, locations or game modifications. Part of the UDK is an integrated editor UnrealEd, which makes modification of the game content even more accessible.