Torque 3D is the best full source, low cost solution out there. It is also our flagship engine built on the core strengths of our Front Line Award-winning Torque Game Engine Advanced. Torque 3D has been re-architected for maximum flexibility and performance across a wide-range of hardware. Torque 3D comes equipped with a full suite of tools to allow your team to excel and produce high-quality games and simulations. With deployment paths to PC, Mac, Linux, you have the power to distribute games wherever they are played.
This is the worst engine ever made by people claiming to be competent engineers. Stay away if you're at all serious about making a decent game.