Option 1: Play your games without a Router, use a sniffer, and write down what ports are used by your games.
Log on the Internet Down load the Data sheets of all major Routers. Check the info about ports opening, and choose the one that fit your ports.
Option 2: Buy the cheapest Router. (Starting tomorrow there will be one on sale for 29.95 AMIR check the usual mega store sales ads.) Put your computer on the DMZ, and enjoy without headaches.