You can export Terragen terrains to various formats which would probably be usable by a game engine. You can export simple heightmaps in .TER (Terragen format, but supported by many 3rd party applications, including some game engines), or .EXR (high dynamic range image format, supported by image editors including Photoshop, which can then be converted to something like TIFF that a game engine could understand). You can also export terrain *geometry*, which will capture certain types of detail (specifically, overhangs) better, but the area of export is limited to the perspective of a single camera. There is no built-in texture export at this time. So Terragen can certainly be used to create terrain for game engines, but it's not necessarily ideal for the purpose.
- Oshyan