A couple months ago, released "RE: Alistair," which is a free OEL dating simulation for Windows/OSX/Linux with a female lead character and three available male characters. Now it's been updated under the title RE: Alistair++, including better art and added scenes. So here's a link to the topic thread on Lemma Soft Forums: http://lemmasoft.renai.us/forums/viewtopic.php?f=11&t=6726
The plot is fairly simple: girl loses a valuable item to another player in her favorite MMO. She does research and realizes that "Alistair," the character who took the item, is one of three guys in her school. And so over the next month, she interacts with the guys and tries to figure out who's responsible.
I describe this as a "simple dating sim" because it's more complex than the average visual novel (stats to build, items to buy, 30 day time limit), but not as complex as any Tokimemo game or Otometeki Love Revo.