Man, that game was barren last time I played it (a year ago, which is still like two years after release.) I guess this is in celebration of the (apparently new) World Leaders mode.
The gist of the game is that Mr. X has invited you aboard his cruise ship, you and several other players, along with some NPCs. The catch is that, once there, he wants you to kill someone else on the ship - if you don't, he'll kill you AND your family. So you play along.
The cruise ship has all the amenities, from bathrooms to on-deck pools (deathtrap) to fancy restaraunts and saunas (deathtrap.) It also has a healthy supply of weapons (umbrella, knife, flare gun, golf club, etc.) You have to find a weapon and kill your target (everyone gets one.) Finding your target can prove difficult, as you have to satisfy I think eight needs (hunger, fatigue, shower-neediness, gotta-pee-itude, etc.) So while you're trying to track down your target (who, like everyone else on the ship, is given a random name to blend in) in a sea of NPCs, you should avoid pooping yourself, avoid getting caught with a weapon in front of a guard, camera, or other passenger, avoid the guy trying to kill you, and maybe get a nice steam.
Rarer/exotic weapons/deathtraps award you with more money, last man/woman standing wins, and if you get busted you are fined and sent to jail. (Money is not just points - you often need to spend it to satisfy needs or bribe guards. Just don't get pummeled while you're at the ATM.)