Not much of a PC gamer, but I have had a need to use a mouse without a desk. I swear by trackball mice. Personally I've been happy with the wireless Logitech trackball offerings, particularly the one with Bluetooth and a dongle you can tuck away into the mouse. Even at a regular desk, doing CAD work all day, it has saved my shoulder and wrist from stress and pain. I can basically sit in a relaxed neutral position and use my mouse wherever my hand falls, like on an arm rest. It may take some adjustment learning to use your thumb to navigate around, but for me it has been worth it.