Occasionally – just occasionally, mind – games choose to add some of our real-world bodily functions to the characters we control in them. Hunger, thirst, even nausea and sewage creation. For some reason, this is peculiarly satisfying, and as such is almost always popular with players: as most strongly evidenced by the popularity of The Sims, with its filling bladders and exponential human smelliness. But it is not just in the human-petting genre that we find such earthy processes: from Stalker's insatiable hunger for bread and sausages to San Andreas' hilarious obesity problem, games occasionally deign to amuse us with the things that we wrestle with every day.
I suppose there are two motivations for mimicking real bodily functions in games (rather than abstracting them with stats such as dexterity and hit points) and the first of those is that they are funny. Yes, it's a fun joke for Duke to take a pee and get some health back. Such are our inhibitions that we find an easy laugh in pooing, weeing, vomiting, and even sneezing, at least where the sneezing produces some kind of mucilaginous projection.
Basic body function comedy has always been a part of gaming – you only need to think back to the 1987 title How To Be A Complete Bastard, with its wee-o-meter and fart-o-meter, to be sure of that.
The darker side of the body-comedy trend is seen in things like people walling up Sims so that they can never get to the toilet, or in the use of pissing as a faintly horrifying attack in the Postal games. Then we reach the aspects of bodily processes which are not funny at all: starvation, drowning, and serious injury.
These processes mark the second reason for games to mimic bodily functions. That is to create game systems that are immediately comprehensible, while at the same time resonating with our experiences. Sleeping in Bully, for example, acted to underline who the protagonist of the game was: a kid. If he didn't get to bed early enough then you'd pass out from exhaustion. The patches that added sleeping back into Stalker: Shadow Of Chernobyl, meanwhile, added in another layer of atmosphere: climbing into a sleeping bag and watching grim, moody dream clips as the time passed. It was unsettling stuff. Atmospheric, but also visceral, because it tapped directly into human things: tired, cranky children; strange nightmares in lonely paces.
Indeed, why should I feel a glimmer of satisfaction at being well stocked with cooked food as my Minecraft character waddles off into his cubic wilderness? Because the alternative - starving to death in a cave – is so bleak, and so threatening. It's a shortcut into real experiences. Games in which we must take precautions against even these most basic of needs are games which challenge us to pay attention, to plan, and to reap the rewards of our preparation and our caution, when we are caught in a difficult spot. They are also games that speak directly to us as normal human beings.
Some games gather all these kinds of mechanics up and put them at the heart of the experience, and the consequence from this sort of design method can yield contrasting results. At one end of the spectrum you get life simulators (like The Sims) and at the other you get tough, dungeon-survival things like Legend Of Grimrock, where eating and sleeping must be dealt with if you are to stay alive. These games, which seem like they have nothing in common, share a fundamental principle in trying to put the needs of guts and brains at the core of their feature set.
Bodily functions, then, are like a foundation stone to certain kinds of game design. We lean on what we know about ourselves to tell stories, or to craft experiences that make sense. From stilling the breathing of your character in a sniping game, to the starving Minecraft Steve, bodily functions furnish worlds that would otherwise lack depth. Every game, you might argue would benefit from a bladder. Indeed, think of how much better the Mass Effect series would have been if the team had needed to nip to the loo before heading down to combat the enemies of life.
Now that would have been something.