>>724030109
It changes a lot. In the vanilla game, it allows you to make love to the girl at the ritual circles. It doesn't add a CG, it's sprite animations like when you marry the other characters. When done with the girl, it takes some of her sanity to boost yours instead of fusing your characters like normal.
It adds a unique ending where you can leave the dungeon without going insane.
It makes it so you can play as the girl. She can do just about everything the other heroes can, but she still keeps the same stats and equipment restrictions. She also cannot do ending B, if you go to the gauntlet it will always be ending A. You can even play as her in Dungeon Nights mode (she can also be romanced in the same mode.)
You can also play as Le'garde if you save him in time and allow him to lead the party.
There are many many grammar fixes and spelling mistakes fixes. Also a lot of bugfixes. There are too many to list, so here is a link to the changelog for the current version:
https://litter.catbox.moe/7r9jeosarvq54vnk.txt
Right now I'm working on an update that will allow the girl to get a unique S-ending.
>>724030527
If you DON'T molest her and max out her affection, you can also get a wholesome daughteru ending too.