Building a whole game engine is a task far from 'ez'. That's why nowadays, you have companies only working on game engines (ie. Unity, Unreal, and so on), and developers taking advantage of that, and why big studios are spending R&D on building their own game engine (Frostbite, Snowdrop, etc) that they can use to build their future games on. The reason why BeamNG.drive uses Torque3D is because it was simply the best solution back then, when the Unity/Unreal/etc. 'indie-friendly' plans were not a thing yet, and you had to pay several hundreds thousand something* to get using them. Keep in mind, that graphics is not the only argument about game engines, which is a common mistake. It generally goes much more in-depth than that (does it fit my project needs? Does the engine work in a way my game can work nicely with it? How does the engine use the system resource, is it good for me? etc etc) Anyhow, this is far from the original question in this thread. For multiplayer, the game engine in BeamNG case is just a fraction of the puzzle.