Complex dating sim games
When the game ends, the player either loses the game if he failed to properly win over any of the girls, or "finishes" one of the girls, often by having sex with her, marrying her (as in Magical Date), and/or achieving eternal love.
Sexually explicit dating sims may fall into the category of H Game or Eroge.
Eroge only gets released to PC because large Japanese game companies do not want to release games with sexual content on their game consoles.
This gives the games more replay value, since the player can focus on a different girl each time, trying to get a different ending.
Dating sims often revolve almost entirely around relationship-building, usually featuring complex character interactions and branching dialogue trees, and often presenting the player's possible responses word-for-word as the player character would say them.