Is using a single VPS for hosting both websites and games ok?

Is using a single VPS for hosting both websites and games ok?

I'm planning on getting a VPS to host websites that I develop for clients,
but I also am thinking about leasing out some of its resources for hosting
a game. Hopefully having a heftier server with more stuff on it will
smoothen out the peak loads.
Details: - I'm just getting into all this so still learning. Willing to
take risks now while I'm in a major learning stage and I'm not handling
super crucial data. - Windows Server, probably 2012 assuming that's the
best. I'm proposing to have it all on one OS. - Sites are ASP.NET, will
run off IIS. A few of the sites will have an MSSQL DB. - Game is Team
Fortress 2 - VPS, so I can easily scale resources as needed
Thoughts? There's a little bit of "games = vulnerabilities" creeping into
my mind, but I can't actually justify that concern.
Or would it really be worth me going for a VPS that does multiple VMs, and
host the games on one VM and sites on another? It's an extra ~$100/month
or so to do that, so that wouldn't really be worth it given you can get a
good game host for that much.