I thought of this as a silly idea, also I made the game cover on canva

(In universe pamphlet advertisement for the game) - "Hello chubster! I bet your lardass has been feeling pretty disappointed seeing no porkers in your video games. Well don't you worry abit come and play Belly Barbarian, ever wanted to live out those nerdy fantasy dreams while still enjoying a burger... Do I have the game for you! Just pure sloppy fun am I right??? Ha I bet your feeling pretty hungry huh? Couldn't last through this without grabbing a snack... typical, don't worry it's normal for a growing boy to pop a few buttons or to have his ass sticking out of his pants. So come on play as Richert Lardzal a handsome young man turned pampered over fed royal fighter as he beats up enemies made from your favorite fattening foods and enjoys his after battle meal. What did you say? You aren't obese? Stop lying to yourself fatboy every guy that dares to touch this game is destined to become a lardball. Enjoy tubs! 🍔🐖⚔️🎮"

Basically you find an old video game that's very obscure and you can't find footage on it, and as you play through the game you slowly grow fatter and fatter with the in-game character... Until the end where Richert(the in-game protag) is now a blob and you? Well you get sucked into the game becoming Richert and now you get to be ever destined fatty that is doomed to constantly gain weight every single time someone picks up the game. Another scenario is that someone else has already become Richert and in that case you're just fattening up alongside the game character but in the real world. The third scenario I'll propose is that at the start you're sucked into the game instantly and not as Richert and you can explore the world and either fatten up yourself, NPCs, or Richert.

Enjoy your adventure gamers ⚔️🎮

(Scenarios)

(1) They finish the game and they get sucked in becoming Richart and are stuck as a fat video game blob for eternity forced to eat enemies and interact with other characters in the game, with this they gain the body of Richart and his traits as well as obtaining his personality and they slowly embrace the world their in, (2) the user finishes the game and is still in the real world but is now obese do too the games magic fattening them up as they progressed so by the end their an obese doughball of themselves sitting in a chair holding a controller, (3) they get sucked int he game at the very begging and play as a whole new character who starts however they want it and they can explore the game world and talk to NPCs, side characters, or Richart and they can romance those characters, help Richart or even fatten him up or themselves up.