The TERRA Engine is quite nice, we've worked with it 2 years ago and even tried to port to XE2 (you may remember that or even find that branch ;-) but because the code didn't match our (to be honest quite high) code standard - if you compiled the engine you'd end up with a lot of "warnings" (despite the compiled engine worked well) we have switched over to unity *cough*.
We would be very happy to see it coming "back" with a proper code base - and if you'd just take a look a the complexity of the engine, Relfos is just right: it does need a lot of more than implementing a 3d engine to be a game engine....

Btw: Relfos, congrats for your Minimon 3D game!