From Moviesandbox

What is Moviesandbox

MovieSandbox is a graphical scripting tool that enables users to script their own gameplay elements. The original idea behind Moviesandbox was a graphical Machinima[1] toolkit. Though, Moviesandbox does not use a Timeline, but allows you to link different elements together in a Hypergraph-like fashion.

MovieSandbox is simple to use and makes use of context sensitive Menus to display only the information needed. It works on top of the game, meaning that you have full access to all of the game's resources and Levels and you can use the game's Tools to create your own environments, or download custom models and Props. Also, Users can extend Moviesandbox with their own actions using UnrealScript and following the Code Guidelines. Moviesandbox lets you save and load your projects. And all of that, without the need to ever close the game, as it's all running in realtime inside the game environment.

MovieSandbox is its own gametype and works with the latest version of Unreal Tournament 2004[2].It is designed to work for Linux, Mac and PC but has some problems saving projects on the Linux/Mac version.

Though originally intended as a movie creation tool, MovieSandbox can also be used to script interactive sequences using either the Keyboard or data received by its UDP interface.