But lot of stuff could be ketp like painting, fullscreen effects, shaders on models or physics !

Could it be terrain based or not from what i've seen you can paint as you want on some model surface, put objects etc ...
This could suit any game using 3D models and nay camera system !

it would be to the programmer to manage distance of view, LOD, optimisation etc ...

Some game examples :
-RPG games cutted into levels glued on to a map :
The Witcher 1 & 2 ! and lot of others RPG games.
- 2.5 D games : platform, shooter, puzzle, Shoot em up
- Adventure games
- Resident evil levels sections
etc ...

So don't worry lot of us could make any of these games types