you could run multiple games on one server, just open another port, install game files, make some minor changes so that the game engines don't clash, and then you have 2 games on the same server.
(it would be nice to get some live stats for the game server load
so you can monitor when high usage is, it might be an idea to run the ticker for the second game on the main server 30 mins past, so that it doesnt slow down (during the hour, there is one time for high cpu usage, TICK TIME
).
But there might be something i have missed :P