I like products of Nomachine company. I was using their some years ago and I am using their today, but I never trying play games through network over NX protocol. I am using free version of Nomachine for Linux and Windows (CentOS 7.1 and Windows 2012 Standard accordingly). Both versions support VP8 and H264 (through non-free codec pack) encoding. I must say that VP8 show very weak results. I recorded sample only with H264 encoding (1920x1200, 60 FPS). Video capture was cause of delays, quality will be better if capture turn off. As result I must say that CPU of client should be as more powerful than I expected (my laptop has i5-4300M).