I've recently watched this anime right through and been smitten by the art style, the plots and the characters.
I'd mainly like to find someone who finds this fresh take on the 'lone high school boy meets five or six girls' theme as captivating as I do.
While a 1-on-1 game could focus on the relationship between Hitagi and Koyomi which I think would be fun on it's own, I could add in Meme, NPCing him and having him act as a guide, mentor and solver of Koyomi's problems... the problems being ones I would feed to the Koyomi player in a form of a puzzle somewhat like the general plot structure of each episode of the anime.
So the simple version of the game could be just the relationship and the complex version could be a game that encompasses a typical story of the average episode.
I would be playing Senjōgahara Hitagi and my partner would play the role of Araragi Koyomi and would be a male player.