Cross-genre games typically take a walk on the mild side. You usually get something to the order of role-playing-game leveling up in a real-time strategy game, real-time-strategy combat in a role-playing game, or maybe a few adventure-style puzzles in a shooter. Generally, the more a developer hypes hybrid gameplay, the more predictable the game itself is likely to be.

Uh, who's supposed to be killing whom here?

But that's not the case with The Ship, a Steam-distributed game for the Source engine formerly available as a free Half-Life mod. Unlike a lot of its hybrid predecessors, this multigenre multiplayer game from Outerlight really is something completely different. While the game draws on identifiable sources such as Quake, The Sims, and Clue, it mashes these elements together with a few new ideas to create an innovative experience that doesn't play like any of its inspirations. It isn't perfect, due partly to a barely there solo mode and partly to the depths to which griefers will sink, but it does prove that there is room left for original ideas in game development.

The basic idea behind The Ship is that you play out a murder mystery on a luxury liner that's decked out in the art-deco style of the 1920s. But this isn't an adventure game, despite the Agatha Christie premise. A first-person perspective and maps loaded with narrow corridors and small rooms make the game feel like a shooter, although instead of blasting everyone in sight, you're assigned to kill a specific victim on the sly for cash, and his or her current location is updated at the bottom right of the screen every 30 seconds. Instead of blasting away with shotguns and BFGs, you mainly do your dirty deeds with improvised weapons such as golf clubs, letter openers, barbecue tongs, and croquet mallets (the more clunky the weapon, the more money you get for using it in a murder). Secrecy is paramount, as you're locked in the brig for a minute or two and fined whenever you're spotted wielding a deadly weapon or offing somebody by closed-circuit cameras or guards (your visibility is indicated by an eye that turns green when in the clear and red when being watched).

Of course, you're not the only murderer on your ship. An unknown fellow passenger has also been given the job of killing you, which means that while you need to keep one eye out for your victim, you have to keep the other looking around for the stranger trying to smash your face in with a rolling pin, gut you with a knife, impale you with an umbrella, or cave your head in with a wrench. Matches are cat-and-mouse games where paranoia is paramount, since you never know which of the other players has your name on his or her hit list. You can even ramp up the goofiness by changing clothing and putting on hats and eye patches to disguise your appearance if an assailant or victim gets a good look at you.

And then there are bodily needs. Just like The Sims, The Ship requires you to sleep, grab a drink, eat a meal, converse with other people, hit the bathroom, and entertain yourself with reading or dancing. Fail to do so, and you suffer some horrible fate, such as dropping dead due to starvation, soiling yourself, going nuts because of a lack of human interaction, or turning into a pile of dust due to dehydration.

Once an action is started, you can't stop, either. This means that you inevitably wind up killing and getting killed in some pretty choice situations. Finally give in and visit the toilet, and the door might be kicked open by a chick with a pool cue. Take a nap, and you might wake up torched by a flare gun. Hit a vending machine for a much-needed soft drink, and you might get your throat cut with a straight razor before you take a sip. Every match features loads of moments that make you laugh out loud, even when you're the one being thumped on the head in the john. The whole situation is gleefully nihilistic and absurd, with the craziness being accentuated by killers and victims who often look like scrunched-up caricatures of gangsters and flappers from the Jazz Age.

Refuse to catch some z's on a regular basis, and you might just fall asleep at the worst possible moment.

Five different modes of play offer variations on the above formula, but only three are really worth playing. Both the one-on-one duel and deathmatch modes seem ill suited to the deliberate style of play that The Ship is best at, so you're best off with elimination, a cautious game with players battling to be the last one alive; hunt, a free-for-all where you respawn again and again and are assigned different targets in timed rounds in a quest to accumulate a set amount of cash before the clock expires; and a solo-only arcade variant. Actually, you're just sort of stuck with arcade, a single-player option with moronic bots who prefer taking naps to trying to kill you, as it is crucial to learn the layout of the six relatively complex ship maps (which range from the small steamboat Atalanta and the little cruiser Batavia to huge luxury liners such as the Andrea Doria and the Cyclops) before venturing online against human opposition.

And online is where The Ship really sets sail. Gameplay is extremely addictive once you get over the learning curve and adjust to the more methodical pace, which requires more sneaking and feinting than the typical online shooter. It's tough to stop playing. You'll typically either get on a great run and not want to stop after whacking three or four victims in a row and accumulating some fantastic weapons. Or, you'll get offed foolishly a couple of times in a row while eating a bag of chips or peeing and furiously keep going to exact revenge.

Matches hinge on players taking the game seriously and going after only their targets, though, which means that you will frequently be sabotaged by jerks who want to play Lizzie Borden and hack everybody up with an axe. Lengthy time spent in the brig after each unauthorized kill does cut down on griefing, though, as does automatically booting players with negative scores (you're also fined for each unnecessary kill). Most matches feature a mature crowd of people out to play the game, not get their jollies out of wrecking things for everybody else. But there are still enough idiots out there that it's impossible to get through an hour of play without getting killed a couple of times for no reason by clowns who think they're deathmatching. Outerlight and Valve have a boot/ban system, but it doesn't seem to be enough to completely get rid of troublemakers.

There are some other quirks, as well. The server browser lists only the map and number of players in each game, skipping vital information such as the mode of play and the length of rounds. Kill descriptions in-game often drop the actual characters' names for ERRORNAME. The video sometimes stutters, online and off. Wash your hands once, and the water bubbles around your torso never go away, which makes you rather noticeable to victims and killers alike. And even though the art-deco visuals are stylish and the ships are gorgeously appointed with period furniture, interiors are often murky. It seems as if Outerlight was going for a vintage, sepia-toned appearance to enhance the quasi-1920s setting but took this idea too far and made just about everything brown and muddy.

Ship interiors are often beautifully appointed but awfully dim and murky.

Audio adds a lot of atmosphere thanks to old-time music parodies (listen closely to the lyrics) playing on cabin radios throughout each ship. But the actual murder mayhem often plays out in complete silence. Killings might as well be taking place in the vacuum of space. This can be very annoying, as you often can't hear the footsteps of some goon running up behind you (on a hardwood deck, no less) swinging a boat oar. Even gunshots are muffled. Someone can be blasting away at you from across the bow of a ship, and you might not even realize what's happening until you're a corpse.

But even while these problems are troublesome, they're minor. The Ship is one of the best and most innovative multiplayer games available right now, particularly at its cut-rate price of $20, and it is developing a considerable online fan base, so you can find a server loaded with players any time of the day or night. This is one cross-genre game that really deserves the hype.