Depending on the orbit, it takes between four and 20 minutes for information traveling at light speed to get from Earth to Mars. So, we're not going to be playing Killzone against Martians anytime soon.
Edge Online's Chris Dahlen talked to some folks at NASA and answered the rather easy question that, yes, real-time communications with a Mars exploration party is impossible, whether that's to say "Hi Mom" or teabag n00bs in Halo. But Dahlen at least goes on to speculate what multiplayer experiences they might be able to pull off.
Obviously Facebook games are a perfect fit, either with asynchronous massively single-player games of the Mobster/Mafia genre, or Flash games with competitive leaderboards. Slow and deliberative turn-based game would work, but when you figure that one turn can take 40 minutes and the Mars team might have chores to keep up with, a title should pack plenty of commands in each turn. (In fact, that's how we drive the Mars rovers today – by giving them a series of orders in the morning and checking back in the evening to see how they did.) And while real-time massively-multiplayer worlds won't fly, you could let players leave tracks for the folks back home to follow – like the time trials in Mirror's Edge, where other players' images race in front of you, or the bodies that stick around in Jesse Venbrux's Deaths.
This is important science, considering we haven't even gone there yet. Hell, by my definition of it, we've only set foot on extraterrestrial soil once during the Age of Video Games. Nolan Bushnell installed Pong in September, 1972; Apollo 17 reached the Moon in December of that year. That's the last time humans left low-earth orbit.
Whenever humans do reach Mars, they're probably going to have a nice long visit, and pack a lot of comforts of home. So there should be all sorts of pop-culture records broken then. First game played there. First beer served on another planet. That sort of thing. Maybe we can finance the voyage with some exclusive sponsorships. Just a thought.
Will We Ever Game Against Mars? [Edge Online]