I assume you mean DDOS (Distributed Denial Of Service) and not Dr-DOS :-)
What can be done to protect my VPS and my game servers from getting "hacked" like this?
1) Don't piss off players. Problem is, the kind of players who are childish enough to rent a botnet are sometimes easy to piss off. Often, a game operator will ban players because they are bad actors (fraudsters, griefers, etc,) and then they retaliate. 2) Buy a really big data pipe into your website. Problem is, trying to provision upstream so you can survive a 50 Gbps attack costs a lot of money. 3) Be proactive about detection. Establish relations with your ISP chain before you need it. When you find a problem, call upstream, and have the problem traffic squelched closer to the source. 4) Buy DDOS mitigation services from a company like DOSarrest, Neustar, Verisign, etc. This costs money as well, but probably less than having to over-provision your bandwidth 24/7.