I see a lot of people struggle to integrate WG into existing game styles that really weren’t designed for such things. It’s hard to make weight gain feel impactful or satisfying without it feeling like a punishment, and the question of how to integrate immobility is one that a lot of developers struggle with. Sometimes the feedee isn’t even the player character, and the WG elements end up feeling a little disconnected from the rest of the game.
The solution is not in figuring out a way around the inherent properties of weight gain, but to embrace them and integrate them into the core mechanics of the game. And the best way I think this can be done is by taking inspiration from a game I have recently been reminded of: Punch Club, a game where you manage a boxer through an increasingly difficult series of tournaments.
In this hypothetical game, you guide the protagonist through a series of competitive eating events, improving your abilities along the way. The objective here would not be as much about gaining weight directly, but more about eating a lot in a short amount of time. The bulk (pun not intended) of the game would be spent in a top-down overworld, not unlike in RPG Maker games, where you spend time working on your stats;
Stomach
The player has to be able to stomach what they eat. Your character has a comfortable stomach capacity, which is how much they will readily eat, and a maximum stomach capacity, which is the absolute limit of how much they can fit in there. You can only exceed your comfortable capacity by so much outside of eating matches, and how far you can go at any time will depend on outside circumstances.
The capacity of your stomach is measured in cubic centimeters. To increase both of your stomach capacities, just fill your stomach beyond your comfortable capacity. The further beyond you go and the longer you stay there, the more your stomach expands.
Metabolism
Metabolism is how quickly your stomach digests its contents, which is measured in calories/time. Metabolism will remain mostly the same throughout the game, although you can temporarily enhance your metabolism with certain items, which will cost (in-game) money.
The contents of your stomach will have a “calorie density” variable. As your metabolism removes calories from your stomach, the game determines the appropriate volume to remove as well, based on how calorie-dense your stomach contents are on average.
This basically means that, even though your stomach digests at a constant rate of calories per second, your stomach will empty much more quickly if you fill it with milk than if you fill it with chocolate or meat. Take calorie density into account depending on which stat you’re trying to improve.
Energy
Energy is a buffer between your character’s stomach and their weight. Your energy is constantly ticking down slowly. Walking and other strenuous activities also consume energy. When your stomach digests calories, they are added to your energy. If you walk around on an empty energy meter, your character will lose weight. If your stomach is digesting something while your energy meter is full, you gain weight. Simple as that. Avoid going to sleep on an empty stomach.
Weight
How much you weigh, obviously. Digesting food while you have a full energy meter increases this.
Being heavier will lower your movement speed, but not the amount of energy you spend per second walking. As you get heavier, walking to places will thus take longer and require more energy. As you grow, consider spending some money on a bus or investing in mobility aids such as electric scooters instead of walking everywhere.
This might make it seem like being fat is just disadvantageous, but most eating competitions would have separation by weight classes. Higher weight classes have more prize money, which you can invest into building stats and managing your mobility issues. Plus, playing as a fat character is most of the fun in these sorts of games.
You can lose weight by leaving your energy meter empty, or paying some money for liposuction if you feel you really have to. For example, you might want to go for the latter option if you accidentally get into a weight class you’re not ready to compete in.
Speed
This describes how quickly you can eat, not how quickly you move. You can improve this by eating solid foods, and this along with stomach capacity will be what decides your success during eating matches. Once you go over your comfortable capacity as described under the stomach section, your speed decreases until you reach your maximum capacity. In the overworld, speed is largely irrelevant.
Much like in Punch Club itself, I think the focus of the game should be on stat management and the eating contests themselves should be mostly automatic. How much the player character could fit in their mouth at once and how quickly they chew would be decided by their speed, and how much they can eat would be decided by their stomach capacity, with some semi-random elements such as pausing to burp evening the playing field a little. The winner of a match would be whoever finishes all the food first. If neither contestant can finish all the food, the winner is whoever ate more.
In the overworld, gameplay would consist mostly of going to various restaurants or other establishments, training your speed and keeping your stomach topped off for as long as you can, as well as managing your money and time to prepare for matches or tournaments that interest you, or sleeping to pass time. The end goal of the game would likely be to claim the title of a long-standing champion.
I’m considering some player involvement in the eating contest in the way of a burp mechanic, in which air also contributes to stomach capacity; as the player’s character eats more, the pressure in their stomach builds and they are forced to slow down. The player could relieve this pressure by pausing to burp, letting some air out and allowing them to eat more quickly. This would bring some challenge into the eating contests by forcing the player to balance not pausing too often and losing time, but also not waiting too long and losing too much speed. I like the idea of this, but I’m not sure exactly how it’d work in terms of math.
I could provide art for this myself but unfortunately I have near zero useful programming ability, so this project will likely never see the light of day unless someone offers to pick it up or help out.