UnrealScript IDE adds many features to Sublime Text 2/3 that you'd expect from a good UnrealScript IDE.
Fully featured object-oriented auto-completion, go to declaration, syntax highlighting, build and run, snippets and some more to name a few...

• Dynamic, intelligent auto-completions

  • fully object-oriented completions
  • context sensitive completions (e.g. in the defaultproperties block you only want to get variables)
  • parameter hints
  • display documentation when you need it
  • completions feel like the great Sublime Text 2/3 snippets

• Go to declaration and back again

  • object-oriented go to declaration (pressing it over controller.GetPlayerViewPoint(a, b) will take you to the declaration of GetPlayerViewPoint in Controller)
  • go to the declaration of the currently selected word via F10, alt left click, right click menu, 'Goto' -> 'UnrealScript Goto Declaration' or search for it in in the command palette
  • when browsing in the declarations you can always return to your starting position by using one of the above keys when nothing is under your cursor.

• Debugger

  • UnrealScript IDE comes with UnrealDebugger integrated.
  • You can set breakpoints directly inside Sublime Text 2/3
  • more information

• Syntax highlighting

  • For .uc files and .log files

• Build system

  • to build your game use Ctrl B, F7 or search for it in the command palette.
  • if the build contains errors, the error log will be opened, allowing you to navigate to your errors quickly.
  • if the build was successful, the game will start

• Launch Game

  • quickly open the game with your last configuration
  • you can chose which map to open
  • chose between Standalone or a Server and 2 Clients or add any other configuration you might like
  • more information

• Various useful Snippets

  • predefined Snippets for standard classes, and language features such as defaultproperties

• Add bookmarks to your comments

  • to add a bookmark write your comments like this: // ! text or /** ! text*/
  • navigate to them quickly via Ctrl R

• More coming...

• Add support for enumerations

• Your suggestion here?

  • You can suggest features, report bugs and vote for features on this site here: UnrealScript IDE - Userecho

Very easy with Package Control right inside Sublime Text 2/3 (Package Control needs to be installed):

1. Ctrl shift P
2. Search for "install", hit enter
3. Search for "UnrealScriptIDE", hit enter

For a more in detail explanation visit the wiki: https://github.com/Zinggi/UnrealScriptIDE/wiki/Getting-Started

Manually (not recommended):

1. Clone or download this package
2. Put it into your Packages directory (find using 'Preferences' -> 'Browse Packages...')

UnrealScriptIDE will only work properly if you add the Src folder as a project.
To do so, goto 'Project' -> 'Add Folder To Project...' -> add the Src folder (/UDK/UDK-201*-**/Development/Src/)

Please refer to the wiki: https://github.com/Zinggi/UnrealScriptIDE/wiki

All credits for UnrealDebugger goes to Carlos Lopez. Huge Thanks!
All credits for various Snippets (and also for the old (now unused) Syntax highlighting file) goes to Michael Alexander. Thanks!
All credits for Syntax highlighting in UnrealScript files goes to Rokit and Eliot. Thanks!
Credits for Syntax highlighting in Log files goes to Rokit. Thanks!

If UnrealScriptIDE is helpfull to you, please consider making a donation. (Especially when you're using it commercially)
Thanks!

Here are some relevant settings for auto-completion that I've found quite helpful:

{
	"auto_complete_with_fields": true,	//this allows auto-completion inside snippets.
	"auto_complete_triggers":	//this activates auto-completion on '.'
	[
		{
			"characters": ".",
			"selector": "source.unrealscript"
		}
	],
	"auto_complete_delay": 0,
	"auto_complete_commit_on_tab": true,	// I prefer 'tab' to 'enter'
}

UnrealScript IDE Plug-in for Sublime Text 2/3 Copyright (C) 2013 Florian Zinggeler

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.