I con’t really think of a lot of games on that site with meaningful weight gain - even on a site that prides itself on transformations, Weight Gain isn’t very popular there. Here’s a few I can think of that’s not been mentioned yet, and their weight gain content is minimal at best.
Accidental Woman has potential down the road if it ever gets a bit better organized. There’s hints of weight gain in it currently, but I don’t believe there’s any dedicated weight-gain events yet.
Lilith’s Throne has potential as well. I haven’t played it in a long time, but I know that does have character weights in it as well as other body part size. However like most other games, being fat/having enormous boobs etc… doesn’t really impact your character’s abilities in any meaningful way, at least last I played.
NewLife allows you to start with a chubbier “womanly” shape, but there’s currently no actual weight gain or means to change your body shape outside of character creation. It’s however one of the best pregnancy-themed games out there right now though.
Apocamorphis I think it supposed to have weight gain in it, but no real way to access it with the limited story content. Granted, it’s been years since I looked at it yet, so its possible that’s changed.
Corruption of Champions and Trials in Tainted Space I know both have minor weight gain mechanics in them. CoC has one or two WG scenes in it but are temporary, and the couple ways you have to gain weight deliberately is to just eat certain foods and only affects your text description. TiTS has even less weight-gain last I recall, just a text description about your character’s weight.
Nimin Fetish Fantasy A CoC style game with some solid weight gain content. You can actually get too busty/fat to move and get stuck in town until you can afford to have it removed. Sadly the game stopped being developed just as the developer was adding some more weight-gain options to it. Still was fun to play though.