Something where inflation is used as a means to solve puzzles. Maybe the character has potions that cause different inflation effects. One for making her like a balloon that can float, one to make her heavy or fat to push switches, and so on. Kinda like the game a boy and his blob but all inflation themed.

To add upon what Drybonesx has said- what if also different body parts could be expanded for different tasks or puzzles.  Belly, breasts, ass etc along with full body.

I've made video games before, and I've been toying with the idea of a free inflation game for the community, but I would probably make use of a soft-body system (As annoying as they are to setup >< ) My idea was that if you are totally deflated you have the highest durability but you cant move very fast (Simple walking etc), whereas if you're partially inflated you could roll around and bounce off stuff. Being inflated past 75% would have you float at variable speeds, but you're incredibly fragile in that state. Late stages of the game would have you very rapidly switching between states in order to bypass obstacles and not get killed by enumerable traps :L  The soft body system could let you squeeze through otherwise impassible areas. 

I think the best style of game this would suit is stealth; Being able to hide in the rafters as some security passes by, or quickly deflating and ducking down under a box to hide from a camera as it whirs along. Maybe even grabbing onto guards to hide them in inaccessible areas at the cost of being much slower to lift from the weight and easily being killed within seconds if you were to be caught. Would be fun ^^

Personally, I'd like to see a game about inflating enemies, like in Dig-Dug, except the game is a platformer, instead of an arcade game. The enemies could just be generic monster enemies, like wolves, dragons, dinosaurs, etc. The player could have a variety of different gases and substances to bloat up enemies with, like air, helium, and water, each with a different effect.

As for story? I don't know, let's just say that it's some inflation fetishist's wet dream, for now.

If I had any amount of programming/art skill whatsoever, I'd make a very simple version of this game.

I personally feel like the only kind of game where this would actually work would be like a really weird Huniepop sort of thing. Like, A strange 'dating' game that people would only really play for the porn/sexy shit, And there'd be puzzle sequences for the sexy shit. In this case, A Bejeweled clone type thing that for every thing you match, the girl gets bigger until she reaches her absolute capacity, Or you can keep playing to pop her.

Like, There would be two ways to play the game, One where you just play it like a normal Huniepop clone. Meet girls, Build relationships with them, Inflate 'em and Fuck 'em, The works!
Or you could do the 'Popper' route, In which you do the exact same thing but blow the girls up wayyy past their limit and burst them. The game would get progessively harder as you progessed in this route but the girls would get bigger with each burst. Like, lets say there are seven girls in a Megaman style selection thing..

Girl 1: The deciding point. Burst her and the Popper route starts, Don't burst her and the game goes on as normal. (can you tell im using undertale for inspiration lmao)
Girl 2: At this point there's been a rumor that girl 1 was popped by someone, So whoever you picked as girl 2 would be a little wary to inflate with you/for you. The puzzle is a little harder, But the payoff is the girl getting a fair bit bigger.
Girl 3: Now things are getting uneasy. The other girls are aware that someone is out there popping people, And won't really inflate with/for anyone they don't know. The game would go into forced inflation territory from this point on. Girl 3's puzzle is a bit harder than the last one, But the payoff is a much bigger size.

from there on it just kinda repeats a bit. The situation gets more tense for the girls, They inflate bigger, And the puzzles get harder with a probable difficulty spike around girl 5. 

Girl 7 would be a scripted event, Essentially when you start the Popper route one of the girls would be unselectable until this point. She knew it was you from the start but she really, Really didn't like the others. So after thanking you for getting rid of them, She makes an attempt to kill you or whatever. This fails, She winds up somehow getting a hose in her ass/mouth/navel/orafice, And thus begins the final inflation. She gets the biggest, Rivaling a five story building or something idk, And goes out in a spectacular explosion. And then the game is over and you win yay.

This was supposed to be a single paragraph. 

fuck.

or y'know just some sort of RPG where the enemies inflate when taking damage and burst when killed, same for your party members.

For years now I've had the idea for a turn-based, text-based, massively multiplayer strategy/adventure game.  I got the idea from a web game called Earth:2025 (now called Earth Empires) that was pseudo-popular in the late 90s/early 2000s.

The way E2025 worked was that turns were generated for all players at a fixed time interval (e.g. 1 turn per 30 minutes or something like that).  You spent your turns generating cash, building up your army, researching technology, exploring, attacking other players, etc.  The game lasted for a set number of days (45-60 days or so), then the scores reset and everyone started over.  Players also had to choose a certain type of government for their country, and each one had advantages and disadvantages in certain areas (kind of like the balance between races in Warcraft/Starcraft and the character classes in Diablo).

My idea for the game was to make the players work through some sort of narrative to achieve a goal, kind of like working through an interactive story except they would be competing against other players.  Then when the game was over, the reset would occur and a new game with a new narrative would begin.  The mechanics would largely stay the same from one game to the next, with maybe a handful of special mechanics that change from game to game.  Inflation could be a good thing (you want it to happen to you), a bad thing (you want it to happen to someone else), or just something that happens to players or NPCs in the game that triggers certain events and furthers the story along.  Instead of government types, players would choose a certain character class that would make them/others easier/harder to inflate.  

It's kind of an ambitious idea, but I think I have the technical expertise to build it.  As far as how to effectively incorporate inflation into it, I have never really been able to connect the dots on that.  It would be hard to make the game interesting: the narrative would have to be fairly lengthy so players don't blow through it too fast, but the inflation also can't be too repetitive or it will quickly get boring.  And I don't want to start busting my ass coding this thing if it's not going to be fun or interesting to play.

If any of that sounds interesting to anyone and you want to help me figure this out, I'm all ears.

The best idea I could think of is a space shooter where the "ships" are actually people (Both male and female) wearing weaponized inflatable suits to take down the enemies. They can also rebound some bullets with their suits, but some will overinflate the suits for a short time, and by this, making your hitbox bigger; and other outright pop the suits, losing a life.

a 1st/3rd person 3D action game about inflation would be totally awesome if someone would do it

in the dancing game there is agility which is reduced by inflation, and passion which grows - this allows certain tricks, like inflating and becoming increasingly aroused and then releasing all your reserved passion on poor opponent overfilling her instantly. While a tabletop game mechanics has just one constant skill rank for swelldance and you can only choose whether to dance or not to dance

in the breathing game you deflate fast by relaxing while letting the air out, and air will be stuck in you if you push it out too hard. In a tabletop you just say that you deflate or keep yourself inflated

the same with all other things. We might argue which aspect of inflation loses most in a tabletop (my bet it's swelldance), but details are always victims of the round system. You say "I attack the orc" rather than "I rise a sword and make a step forward"

Okay, a good Game Master might compensate that by describing details, but it's so cool to control things yourself! I think the 3D action game will be wanted no matter what for a very long time! ^_^

well, there's many things i'd do, but i think one i would really like would be a action platformer. you'd play as a lass who has many ways to inlfate herself to solve puzzles and what not. sure it's been done before, but here's the old, sugarhigh twist! She'd only be able to hold her size for a bit before deflating, so you'd have to plan things out! (what this means for me is a meter that would be be her face, getting puffier and darker the longer she holds.) my own messed up kinks aside, it'd be fun to no you only have a small amount of time to get what you need done, and adds some puresse! i'd be awful at the game, myself, lol!

I once tried to get a fighting game started but Pballooned didn't want to to continue working on it, which I guess I can understand, took him about six months just to have four fighters in it. This is what so far got done. https://www.dropbox.com/s/pn3w9a5wfimi7qm/IInflatable%20Sumo%20Girl%20League.zip?dl=0

Some platformer adventure/puzzle game where you can inflate baddies/willing allies and in some cases yourself to move along. Let's say you can incapacitate someone by inflating them into a sphere with one pump. If you inflate yourself, you roll along until the inflation wears off, virtually invulnerable.

Inflating twice makes them float, inflating three times makes them float higher, but also makes them more fragile, also they only stay that inflated for a short time before deflating to a smaller size. (I guess they could pop or rapidly deflate with a "pop!" sound effect if you stand on them for too long.) While they're inflated, you can use them as platforms.

In your case, limited time inflation is the same as flight, with two pumps letting you fly a little distance, and three going higher, but harder to control and also you're very vulnerable to spikes on the ceiling.

The game I'd make would be about a 16 year old girl named Trinity, who volunteered for a science experiment which went wrong. The failed experiment gave Trinity the ability to stretch and inflate. Now with her new powers, she has to find her kidnapped friends by solving puzzles. Trinity must use the ability to inflate for flight or bouncing enemies away from her. 

Trinity's stretch ability is used for throwing heavy objects at enemies or just moving them out of the way. She can also use them for attacks.

Her special ability is the ability to inflate with propane gas. She inflates with propane and pops herself, creating an explosion and mysteriously turning back to normal after the pop. 

When the enemies discover the girl's new powers, Trinity has to avoid sharp objects while inflated or else she will pop. Enemies will try to inflate her past her limits and cause her to explode.

Anyway a game using inflatopn as a as a core mechanic would be cool. But I don't see it happening anytime soon.