Quote from MotiveMe (cortexrp.com/beta/?page=about):
Cortex is a roleplaying map for Starcraft II, Blizzard's latest real-time strategy game. In a roleplaying map, the players create their own storyline to go along with anything they create, and interact with other players to move the story forward through time. Because of the highly dynamic nature of roleplaying maps, Cortex focuses on making it so that you can do everything possible in-game that you would otherwise need the Galaxy Editor to make. You accomplish this highly customized creating through the use of specialized chat commands such as @spawn to create units.
Cortex is a library to provide players with an in-game sandbox with a significant amount of map and unit manipulation. While directly intended for roleplaying, Cortex can be used a general sandbox for things like attachment testing, in-game scenery creation, and unit testing. Cortex is coded exclusively in galaxy and is open source. Mappers can freely use and modify the code.
Cortex was initially developed primarily by Motive / MotiveMe (original sc2mapster asset and team). Later there were significant updates by Spritelayer. I have since unofficially taken over development of the Cortex library. I refer to my contributions as Forge Extensions because I was unsure of whether the changes would be directly implemented in the engine. The code will remain opensource and public. Briefly, features I've implemented include:
Per-unit commands caching system
System for loading/saving units (along with all relevant commands applied on the units)
Blacklists (per-game-host basis)
Mouse-click model actor placement and manipulation
Cortex with the Forge Extensions can currently be tested on SC2 maps Cortex Roleplay - Essence (terrain by Fruity) and Cortex Roleplay - Swamps (terrain by Piekan) on NA Battle Net. More maps will be including Forge in the near future. I do also have eventual plans to officially implement the Extensions into Cortex as Cortex 3.0.
I am open to bug reports, feedback, and suggestions.