The focus is much more on stuffing than weight gain (though there’s still a decent bit of the latter), but I’d be remiss not mentioning Some Bullshit by Nerds.
It is I believe the current pinnacle of blending fetish and narrative, an utterly massive 30+ hour RPG experience with a lovable and well-developed main cast, effective comedy and drama, surprisingly decent gameplay for this type of thing, huge amounts of assets, and loads of opportunities to get into food/belly-related hijinks.
I’d easily have shelled out 50 bucks for it if were an unironic public release on Steam or something lol. Can’t sing its praises highly enough, the gold standard on this site IMO. Legitimately it is so well written and paced that I think it’d make for a decent experience even for folk not interested in the fetishes it covers.