Game mode automatically turns off TruMotion, but it did leave the autodimming option on. Once I turned that and "Real Cinema" off, I got better results.
One slight annoyance, and I'm not sure if this is standard on all 3D sets, is that every time you launch a 3D enabled content this obnoxious prompt comes up telling you to put your 3D glasses on. It stays up until you click OK on the TV's remote control. I'm trying to find the setting to turn that off, but I don't think you can.