Quickstart information about developing a mod in UDK here.
First of all - install UDK. Note that this guide was written for UDK version July 2012 (UDK-2012-07), but it should hold for other versions as well. Get UDK from www.udk.com .
When developing a project in UDK I strongly recommend to use Visual Studio along with nFringe.
To assure your new game or mod get compiled properly you need to tell UDK it should compile your mod as well. You do this in the file UDKEngine.ini
(located in UDK-2012-07/UDKGame/Config
folder). Find the part below and make sure it looks like this:
[UnrealEd.EditorEngine] EditPackagesOutPath=..\..\UDKGame\Script FRScriptOutputPath=..\..\UDKGame\ScriptFinalRelease +EditPackages=Core +EditPackages=Engine +EditPackages=GFxUI +EditPackages=GameFramework +EditPackages=UnrealEd +EditPackages=GFxUIEditor +EditPackages=IpDrv +EditPackages=OnlineSubsystemPC +EditPackages=OnlineSubsystemGameSpy +EditPackages=OnlineSubsystemLive +EditPackages=OnlineSubsystemSteamworks +EditPackages=UDKBase +EditPackages=UTEditor +EditPackages=UTGame +EditPackages=UTGameContent +EditPackages=YOUR_MOD_NAME
where YOUR_MOD_NAME is the name of your mod. Then you can compile code by manually calling “udk make” (Binaries/Win32
folder) or by building project in Visual Studio.
Note: +EditPackages=YOUR_MOD_NAME should be the LAST +EditPackages record in [UnrealEd.EditorEngine] (otherwise there could be problems with dependencies!)
This assumes you have already set up your mod and created subclass of GameInfo class that is used for launching your game. To run your game simply type in console “udk DESIRED_MAP_NAME_WITHOUT_.upk?game=YOUR_MOD_NAME.YOUR_GAMEINFO_SUBCLASS_NAME” (Binaries/Win32
folder)
To run UnrealEd call manually “udk editor” command from Binaries/Win32
folder.
Dungeon Defense is an example of a game built entirely on UDK. Its open source, so it can serve as an inspiration on how to do things in UDK (note however that is was built using older version of UDK).
There are many online sources and large community around Unreal and UDK.