Haha yeah, they're definitely a bit more niche but keep them in mind when your game shelf starts to run out. Though TLS alone will easily last you a long time.
If you liked Overwhored you will probably like TLS and Roundscape, they are somewhat similar in gameplay as well built RPGM games (though not in story). Divine Dawn (renpy) and Love and Corruption (HTML) are a bit different, but also worth giving a shot to see if you will enjoy it.
The Last sovereign is the best one by far IMO. Other nice ones are Roundscape Adorevia, Divine Dawn, Love and Corruption and Overwhored (This one is really old and I can't remember if it's actually good)
Yup, Illusion games are the way to go if you want a full 3D model of your character you will use throughout the game. Though some like Honey Select are barely a "game" by themselves. I would recommend something like KK or even AA2 (If you're okay with older graphics) if you want gameplay that is...
Most game with a sports/school setting. A couple ones that come to mind that have plenty are:
-WVM
-University of Problems
There is more but I'm blanking.
This happens unfortunately too often. Lots of devs think they will make a long epic at the start but fall out of love or burn out halfway through. But well, at least the rushed ending is still better than the abandoned tag.
I'm not gonna lie, I don't know many of those by name. But striped socks would be my favorite of the bunch, though I am a simple man who prefers no socks or any kind of clothes.