If they're trying to avoid boredom, Star Trek Online is probably not the best solution.
In fact MMORPGs seem like a bad idea when your latency to the server is measured in minutes, and it's hard to imagine a Massively Multiplayer game when you're talking about a crew of 4-6 people.
The idea that astronauts will need some games to pass the time while on what is an extremely long flight seems like a bit of a no-brainer to me.
They probably won't even have much work to do. Most of the time is spent just watching the distance counter tick down. They probably can't bring too many experiments with them on the trip, because the per-lb costs for a Mars launch are astronomical, even by space standards, and most microgravity experiments can be conducted in satellites or the ISS much cheaper.