@viragomann Game server is on Interface 2, Client is on the OpenVPN interface. Here's a quick layout of my network:
Interface 0 - WAN
Interface 1 - 192.168.0.x
Interface 2 - 192.168.1.x
OpenVPN - 192.168.2.x
Interface 1 an 2 can reach the internet through WAN/Interface 0, but generally can't talk to each other (with some exceptions made in the firewall).
Locally, a computer on Interface 1 can play games with computers on Interface 2. I just looked for the ports that were requested and opened those up on the firewall. Additionally, computers on Interface 2 can talk to a file share on Interface 1.
Using the VPN, I copied the rules used for the file share and gaming (on both the physical and OpenVPN interface respectively) to do the same thing for OpenVPN clients. I'm able to connect in, and from the OpenVPN client I can connect to the file share on Interface 1. I'm able to ping the game server on Interface 2, but when I try to run the games they server isn't visible in the game.