Art, story, characters in that order. I think those are the most valuable parts to any good porn game. I can take or leave animations since they sometimes cut into the quality of the rest of the game for the sake of making animations. Customization does not matter at all to me as long as the listed 3 are quality.
Its all about the story.
Love of Magic has a great story and I bought it off of steam and now have well over 1100 hours of play in all 3 books.
Sisterly Lust 200 hours of play and it also has a good story, bought it on Steam.
2-3 free ones on Steam.
There isn't one specific reason; it would actually be easier to list the reasons why I *wouldn't* pay.
Having a coherent story, reasonably well-crafted characters, and avoiding unnecessary, tedious clicking is essential.
It’s not mandatory, but it helps tip the scales in favor of buying.
Beautiful art, well-executed sex scenes, a diverse range of girls (in terms of appearance and fetishes), and choices that actually make a difference.
If I genuinely wanna support a dev for making a banger. Sinisistar 2 is an example of this. Game was just that enjoyable that I wanted to support the dev.
After playing? Usually a unique, exceptional gameplay loop that feels like it can set the standard for future h-games. I want developers like that to keep creating.