I don't have any proper recommendations for mainstream games, but I will of course shoutout the excellent TFGames for your NSFW browser (et al) game needs.
Otherwise, there's certainly something to be said for even playing games like Animal Crossing or Stardew Valley but choosing a girl. It's not the humiliating experience you might be looking for, but it can be fun!
At first I thought this was a post for indie gamers/devs to find specific sissy training games, and I was surprised to hear that Nintendo released one. Oh, if only.
I had a recent fling with a chastity bottom who played Elden Ring and stuff, but that probably means he's not a real sissy.
I recommend the Barbie Horse Adventures series, available for Game Boy Advance, Nintendo DS, PlayStation 2, Windows, Wii, and Xbox. I also personally enjoy the Princess Maker series (though that targets a broader demographic) - available for PC, PS2, PSP, Switch, and mobile.
In the browser: 🖥️
Secretary: the game is the biggest baddest sissy narrative game I know of. The story goes on forever - I gave up after like 4 months.
A series of games are sold by Mia, the enterprising sissy who runs Hypnotube. I haven't played them.
Fap Roulette is always waiting for a roll...
I guess there are mainstream games that are feminine (eg, Barbie) or that can be played in a feminine way (eg, pick a feminine character) and then there are also explicitly sissy/sexual/feminizing games.
For the second option, I've enjoyed Perverted Education from TFGames, the site K.K. already suggested. Check out the site's advanced search adult theme and transformation theme options
I finally found the exact game I played a lot back when I was restricted from playing anything not sissy-appropriate. It was for Nintendo Wii like I said, and the title is Bratz: The Movie which was obviously based on a movie that had come out back then.
I also recall I tried a Barbie game, and based on release date it was probably Island Princess but I don’t recall anything about it.
But now I’m on a roll of recalling things and one other game was Kitty Spangles Solitaire on Mac.