Some Japanese dating sims may allow the player to have romantic or sexual relationships with characters in their teens.
There are many variations on this theme: high-school romances are the most common, but a dating sim may also take place in a fantasy setting and involve such challenges as defending one's girl from monsters.
One game series that often includes dating, with the goal of marriage, is the farming sim series Harvest Moon.
Founded in 2002 by Nobel Laureate Carl Wieman, the Ph ET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations.
Ph ET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.
This gives the games more replay value, since the player can focus on a different girl each time, trying to get a different ending.