‘Hunger’ is one of those things that isn’t used much outside of… roguelikes, basically.
Well, I suppose there are those games (almost always MMOs) that use hunger as a sort of debuff, and those who use food as a sort of buff instead (usually healing).
There are also games like the Sims, but in that case hunger rarely becomes an actual issue; it’s just another mundane thing you have to keep doing to keep up happiness and not die (which, you know, is fine and all. it’s just not what I’m talking about much!).
In both of these games — MMOs that use hunger and the Sims — hunger is a chore. I don’t necessarily mean this in a bad way, but hunger is never an interesting decision. It’s a reaction. You get hungry, and you eat whatever. It rarely even matters what kind of food it is. Or, in some cases, you get low on health and ‘food’ refills it by putting you into a ‘food state’.
So that, in a nutshell, is hunger as a chore. Not very interesting. Hunger can be much more than that, but it’s a difficult line to walk.
To bring up the easiest examples, almost every roguelike has hunger (well, aside from the very short-form roguelikes which can be quite cool in their own way). The first way it’s made a ‘challenge’, and an interesting one, is that you can’t simply buy food. Food isn’t a matter of ‘stock up while you’re in town’ or ‘make sure the fridge doesn’t run out’ — occasionally you have to go hunting, but more frequently, you realize your stocks are running low and you must press on.
In many roguelikes an additional challenge can be found in food with negative aspects: some creatures’ meat may poison you, or you might not be able to eat meat, or depending on your race you might only be able to eat meat (and not all those tasty fruits that are lying around in a dungeon for some reason). Other times you starve to death disappointingly, but quite often this is an avoidable fate.
Really, however, Hunger is usually a glorified timer. Like the ghost that appears in Spelunky (and Spelunker, I believe) if you spend too long on a level, all timers have warnings. For hunger, the game generally just tells you ‘YOU ARE HUNGRY’. Ghosts make creepy music (in Spelunky anyway) in lieu of their arrival, and simpler timers based on visible numbers will just have those numbers turn red.
In some games Hunger is a good thing and I think this is something to be avoided. In an old game called Secrets of Asherah (from when I was a tiny, tiny human) you could only drink potions every so often. For some reason this would make you “full” and you’d have to wait a while. To be honest, I’d advise against this… it’s frustrating when consumable items have a (rather long) built-in cooldown timer (especially when they don’t have a very convincing reason why).
Back to Hunger as challenge. There’s a series of commercial, non-ascii roguelikes called ‘Shiren the Wanderer’ — in it, you feed yourself via rice balls and die if you don’t keep yourself well-fed. Other games have their own ways of keeping hunger interesting, but this game’s are generally different. As the rice balls are a very clear entity (there are big rice balls and small ones, but they’re all the same thing), they can be targets of enemies, traps, and more. Certain enemies convert random items in your inventory into rice balls (which can be good or terrible!) and some traps turn rice balls rotten (I think it’s a water trap, oddly enough).
I do have to end by making a point (unfortunately) so here it is:
Hunger (or its opposite, ‘fullness’) appears in many games as a value that must be constantly sated so as to avoid death or at least unpleasant effects. However, where in some games it is the basis for a valued resource or a force driving you forward or into risky situations, other times it can be a timer on the sideline preventing you from regenerating health or acting at full strength. Yet other times it is a chore. As a part of design, ‘hunger’ could be many other things, but at its heart it is a facade laid over the interesting concept of a constantly-draining stock that must be maintained.
To be honest, hunger is one of the least interesting of such stocks, because it doesn’t interact with anything else. A robot can have energy that’s used as a timer and as a resource. In a way, combo meters are similar things (oddly enough — they’re just way faster); you need to do something (usually hit or kill enemies) to maintain it. Fail, and you are punished (loss of score multiplier).
I think that, if I’m going to make a point, it’s this: Make TIMERS interesting. Hunger scratches the surface, but if you want to spice up a system with a timer or with hunger, there are a lot of ways to make it interesting. If food is scarce or some of it is risky or (especially) the player’s able to revisit old locations, you can be sure that hunger will keep the player on edge.
Just don’t forget to tell them when their stomach is growling.