It isn't what you're looking for, but I bought one of these so I can use my laptop to watch hockey while I play games. My router is on the other side of the house and on a different floor so my wireless is terrible. I put one of those in my room and the other one is plugged in near my router and connected through Ethernet. I don't use it for gaming so I can't really comment on the performance, but my connection is just as stable as my wired PC and I get my full download speed (~28 Mbps) from it when streaming video. Since it uses your electrical wiring for the network connection the performance can vary from house to house, but my connection is surprisingly outstanding with it. You can connect to the WiFi part of it with ethernet so you will essentially have an ad hoc wired connection.
I'll second the powerline adapter recommendation here. If you absolutely cannot drill holes to run cable, then powerline is the next best thing. Just make sure that you're plugging in to power outlets that are on the same circuit, and that you are plugging directly into the outlet, not a surge protector or some sort of intermediary.
The nice thing about the powerline adapters is that they double as wifi access points, so if nothing else, your wifi signal should improve. I do find that they have to be occasionally unplugged/replugged, though.
