To Heart started off as a hentai (adult)
visual novel PC game. Studio Leaf made the game in 1997. You play
Hiroyuki as he goes through high school and interacts with the girls
there. Since the game is a visual novel instead of a normal dating sim
game, the story is mainly told through the art since instead of speech,
which is why in the To Heart game nothing is spoken to you.
The
playstation adaption of the PC game is just a non-hentai version of the
game. For what I know so far about it all the elements are still there,
minus the hentai scenes. The game was done by Aquaplus, Studio Leaf's
sister company, in 1999.
Even
though Queen of Hearts isn't an official game it has gained some
popularity with To Heart fans. Queen of Hearts is a parody game which
has the To Heart girls, with girls from other Studio Leaf games, fight
each other street fighter style. There is a '99 and 2000 version of this
game out.