Harukanaru is a shonen ai game in Japan made by Koei. It has inspired manga and an OAV. The game can only be played on the Japanese PS and PS2 systems but I have seen it for sale on eBay as well as some of the other merchandise tie-ins to the game.
I don't know much about Haru itself but I'm in love with the artwork. I discovered it by happening upon some of the pencilboards and an artbook at an anime convention and was struck by their beauty. Naturally, I had to make them mine.
I currently own 7 of the pencilboards, which are here:
I'm hoping to scan and load some of the images from the artbook as soon as I figure out how to get them scanned without breaking the book's spine.