QuoteIf TG2 would have this kind of preview, work would be much easier to do
Sorry, wouldn't work.
Crysis, since it's a game, is made with incredibly low-poly objects (seriously, those trees become "billboards" (single 2-poly squares with pictures on) at very short distances. These pictures have to be created by somebody, and can't be done by terragen on the fly).
The water is spectacular, as it always has been with crysis, but not very customisable. And as a level editor itself the sandbox is highly limited.
Thirdly, all that high-poly detail on the terrain is created from normal maps (possible displacement maps) in the terrain textures, and not pure geometry like in Terragen. Since terragen doesn't use normal maps for microdetail, it wouldn't be able to render these in the preview in real-time either, since it would require a great deal of processing to create the maps themselves.
It probably doesn't have global illumination settings either (it might, but i doubt it).
It certainly wouldn't be able to render an entire planet.
The main point I'm trying to convey, is that whil crysis looks superb, and in real-time too, all of this content that you see is created outside of that editor (textures, normal maps, models) and not in real-time. For terragen to present that quality in real-time it would need to use the multitude of shortcuts used in the game industry, and so we'd all have to be making normal maps in photoshop.
I'm sure somebody with a greater deal of game knowledge/programming knowledge can furnish you with greater details (I only have game-creation experience, no programming).
