I thought it'd be fun to list some BxG games that were made with Ren'Py. Now those listed here are only ones I have played/am playing, and I will probably update it periodically, but feel free to contribute to this thread with your own lists!
Requirements to be on the list: male protagonist, female love interest(s), and made on the Ren'Py engine specifically. Both multi-branching and kinetic novels are included. If you wish to include non-Ren'Py VNs, make a separate list in your post.
Warnings will be put if the novel has an NSFW version for those who may wish to avoid that sort of content (like me lol, I'm not a fan of those I only made an exception for KS because you could turn it off). If you include any NSFW links please put a warning!
Hope this list helps you find some good bishoujo/BxG titles!
A Fireworks Meeting by AsHLeX
After Guardian Angel by z-ish.p
All I Want for Christmas is a Girlfriend by PixelSoft
Broken Sky by denzil
Café Memoria by PixelSoft
The Cute, Light, and Fluffy Project collaborative project featuring 4 stories, 2 of them BxG which are "Cuter than Fiction" and "Five Minutes"
Crop Circle by azureXtwilight
Digital Seclusion by Zalor [ CAUTION: has some borderline explicit sexual descriptions in a couple places, rated M for Mature ]
Do Not Love - Violators Will Be Shot [DEMO] by teambisugo
Dual Hearts by Radical Dreamers 2002
Flowers which Bloom in Winter [DEMO] by Yotoge Collection
Forget Me Not by sake-bento (aka sakevisual)
Her List by Cami
Homeword One Story by Love in Space [ WARNING: link to the NSFW is here too ]
Katawa Shoujo by Four Leaf Studios [ WARNING: Full version is NSFW - sexual content can be turned off but not nude sprites ]
Letters for You by Patty [ link is broken but I still had it and posted it in the thread here ]
Looking Up to the Earth by JonFawkes
Lost Impressions by ds-sans
Lucid9: Inciting Incident by Fallen Snow Studios
Memo by Doomfest [ Mediafire link is still active ]
Moe Era by ComfyCompany
Moonlight Walks by American Bishoujo [ includes original 2005 version within the Extras menu ]
Monochrome Valentine by Team Kizuna
One Thousand Lies by Keinart
Ori, Ochi, Onoe by ATP Projects [ CAUTION: there is no nudity or explicitly described sex, but sexual content is present, rated M for Mature ]
Palinurus by Watercress
PenPals by NeumanProductions
Project Nattsu by Lux Visual Novels
Ripples by sakevisual [ you can also still play the original release ]
Sepia Tears by Scarlet String Studios (formerly Team NEET) [ also has a Reprise Edition ]
Songs of Araiah by Bishoujo Games
Sounds of Her Love by ds-sans [ a sequel also exists ]
Student Union [DEMO] by Visual Novel Village [ CAUTION: intended for mature audiences only, M for Mature due to violence and suggestive themes. The full game plans to have an optional H patch ]
Sunrider: Mask of Arcadius by Love in Space
Sweet and Spices by Pastelle Studios
Tales of Lemma 1 by Lemma Soft [ also has a remake ]
Time Labyrinth by mochalematazi
Non-Renpy Titles
Aselia the Eternal by XUSE & JAST Densetsu
eden* by minori
Locker of Death by Genius Studio Japan Inc.
May Sky by Scrubbing
Narcissu by stage-nana
Steins;Gate by 5pb & Nitroplus
We'll Meet Once More by Genius Studio Japan Inc.