CATHODE is an engine built by The Creative Assembly for the 2014 video game Alien: Isolation. It is a highly modified version of the engine created by The Creative Assembly for an earlier title, Viking: Battle for Asgard. The trademark for the engine name was filed by SEGA on August 26th 2013, and eventually granted on the February 20th 2014.
The CATHODE engine was built upon a custom scripting system which was created entirely for Alien: Isolation - named after the engine, "CATHODE". This scripting system was "live edit" and allowed for the use of prefabs to quickly build upon existing code. The editor was created in a WYSIWYG format allowing for easy modifications by the team. The CATHODE scripting system covered: particles, lighting, props, AI scripts, audio, zoning and character setup.
Lead developer Clive Gratton has explained how difficult it was to develop Alien: Isolation initially as CATHODE was created. Due to the engine being unfinished as production on the game began, there was consequently a period of around 6 months of work that was effectively lost and entirely rebuilt in the new scripting system when it was ready for the team to use.
Deferred Rendering
The engine was built to use a process known as deferred rendering which allows the developers to use a large number of lights in an environment along with advanced geometry and maintain a constantly good framerate. This meant that the game was able to re-create the Alien look without being too taxing on the system it runs on.
Early Versions
A screenshot of the CATHODE script editor in action.
The CATHODE engine is a highly modified version of an engine created by The Creative Assembly for a previous title, Viking: Battle for Asgard. This engine was likely chosen as a base for CATHODE over their Total War engine due to the third person perspective of Viking and the large open environments it could render. The giveaway that Viking: Battle for Asgard's engine is the base of Alien: Isolation's CATHODE engine can be found in Isolation's console build, where many Viking config files are left over - such as UI scripts, weapon scripts and attack data.
An example of realtime performance metrics.
An example of the realtime artist profiler.
This was later confirmed by Clive Gratton, Alien: Isolation's lead programmer, in a talk explaining how Viking's engine was reworked to become CATHODE. Aside from the new features added to the engine such as deferred rendering, behind-the-scenes a number of new tools were created to use with the engine, the main tool being the CATHODE script editor. This editor was similar to the blueprint system found in Unreal Engine 4 and allowed programmers to easily script elements of the game through a custom tailored interface. Clive spoke of issues faced in early development, particularly developers creating elements of the game before the script editor was finished, which meant those elements then had to be re-created when the editor was ready. This slowed development and meant a lot of work was wasted.
Trivia
- The mod tools created to open Alien: Isolation's PAK files also work with Viking: Battle for Asgard due to CATHODE being a newer version of that engine.
- The deferred rendering that was added to Viking's engine for Isolation was first previewed at the 2012 "Develop Conference".
- The original main menu for Alien: Isolation (for pre-release demos) included a boot logo for CATHODE, but this was cut from the retail version of the game. The boot logo can be seen at the top of this article.
TOP LEFT: Albedo, TOP RIGHT: Normal mapping, LOWER LEFT: Shininess, LOWER RIGHT: Fully-lit scene!
Further Information
Further information about the engine can be found at the following links: