I can run Borderlands on a really old 3D card having minimum shaders , the game is Unreal 3 engine.
Well for next generation, i think Unreal Engine will ask more recent 3D cars at minimum.

some 3D AAA games, even recent can be tweaked a lot to run even on very low 3D card having basic shaders !
Some will run icreadibly slowly, but will run if you have 5 years old 3D card !

Some indie engines targetting only latest 3D cards, i think don't have understood the point of PC market , but it's a choice !

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All depends on what game you target ?
If you target Crysis like or today full of polygons , physics, eye candy effects, then yes you will target some hardcore players having latest 3D cards from 3 recent years !
In that case take the Indie Engine that responds to that demand perhaps ?

I'll check another time, but i don't think Torque 3D needs such 3D card for nay game ? Specially if you use only terrain and basic 3D models and lightening ??