Red Alert 3 was created using Electronic Art’s (EA) Sage Engine.
The Sage Engine utilizes 3DSMax as its main application for creating art. There are 4 main tools that are used in 3DSMax: .W3X Exporter, w3d Skin modifier, w3d utilities and w3d materials. These are generally referred to as the W3D tools.
The W3X viewer allows the user to view the W3X files exported from max before bringing them in-game.
The Sage Engine also uses WorldBuilder, which is a proprietary application for the creation of single-player and multiplayer maps for the game.