What is a good game engine with solid network support?

Can you suggest a 3D engine for a near-trivial first person game that needs to support nonstandard input?

• While working out on an elliptical machine I realized it is really boring looking at the wall/tv/etc.  I found the API that the elliptical uses to send info (speed,etc...) to the PC, and it is very easy to use. So what I'd like to do is take a 3D or game engine, select some premade world, specify a path within the world, and apply the velocity signal from the machine to update (x,y,z) and maybe point the camera at the next waypoint.  Maybe also throw some realtime statistics on the screen as well. I've glanced at some of the "new" (they're new to me) game engines that are out there.  This would be a zero-budget, just-for-fun project, so I'd want something free to use.  The idea of mapping the output to a wearable display like the Oculus Rift sounds hilariously fun. I glanced through a few tutorials for Torque, Cry Engine and UDK. They all seem more than adequate for what I need, except I'm not sure about how involved it would be to supply velocity (which would come from a USB CDC that I'd get from polling in a C++ thread). Any thoughts before I start?

• Answer:

  Unity is popular for this sort of work.