Viva Caligula is Latin, or Italian or Spanish maybe, for "Live Caligula" -- if you're the founder of Penthouse this means making a movie with lots of nudity and depravity; if you're Cartoon Network and a (regrettably) anonymous contracted developer this means making a game with lots of violence and depravity. (Ed.: maybe not credited, but this is by Pop & Co., who also created Bible Fight.)
Note: both the film and game have some violence and nudity respectively, but its kinda significant that they're proportioned inversely -- are games more inclined toward violence and movies toward sex? Or this just a cultural loop the means of production are caught on?
The game is a top-down, Zelda-like crawl with a twist of Satanic rage. You play the titular emperor, who runs around killing everyone to purge the city -- like Stalin, but less efficient. You use the arrow keys to move, but the attacks are what's interesting -- every key on the keyboard, all 26, are mapped to different weapons that you pick up, with the goal being the collection of all of them. While some are basically re-skinned copies of each other, the diversity is still non-trivial and pretty profound, and you can come up with entertaining combos like setting people on fire, then practicing necromancy to swarm out the rest of the screen. This causes some difficulty: the hand tends to rest the fingers (at least for me) on the A,S,D,F set, so beyond these and the other eight or so that are easily reachable from this posture, you're going to have to consciously move your whole upper arm. I know, I know, but we're talking about split-second movements here, it makes a difference.
Possibly the coolest feature is a microphone utility that allows you to charge your rampage meter by yelling. This allows you to really roleplay the deranged psychosis of Caligula as he perpetuates mass murder for the hell of it; there's also a bit of a DBZ vibe to it, for which you may have, like Caligula for his horse, a fetish. (Ed.: Pace Suetonius, a myth. But never mind.) Jamming Manson in the background can help save your vocal cords.
When you get all the items, you enter the palace; instead of the closure that you'd expect in most games, you're given the denouement of an orgy, complete with blurred, cartoon nudity. Just walk over someone and they light up, causing you to both figuratively and literally score. This counts for the guys too; the arbitrary indiscriminate nature of the bisexuality here is very Roman. (Ed.: No it ain't. This is very Greek. And, of course, another indication of Caligula's depraved nature, in that he's forsworn Roman virtu in favor of the dissolute behavior of the intellectually superior but otherwise decadent subject culture.)
Despite the frags-and-fags culture that prevails in hardcore gaming, this kind of romp is probably the best approach to sexual diversity seen in games. Instead of letting gay players marry a guy, Temple of Elemental Evil-style, or letting lesbians enjoy a fully-rendered alien sex scene (http://www.penny-arcade.com/comic/2007/09/19), or letting straight guys get with hot chicks or straight girls get with buff men, you offer the democratic solution -- everybody will fuck everybody.