Heartache 101 ~Sour into Sweet~ is the world's first romance simulation expressly designed to allow for expandable content. In other romance simulations, commonly called "datesims", there is little reason to ever play the game again once you've pursued all the characters you're interested in. But Heartache 101 ~Sour into Sweet~ has a cast of characters that is completely open-ended. You can add characters to the game that were created by other users, or create new characters of your own!

Images for custom characters can be generated from a template using an application such as Photoshop or Gimp, or from art you have created yourself, or from any source. (only "standing" images can be imported; there is no event CG in the game) A simple scripting language is provided for writing story events so that you can create story for your character(s), or add onto story created by others. You can also customize much of the music.

The game system itself is in part a visual novel interface with gameplay that include conversational decision-making, board game-like mechanics, stat management, financial management, and more.

Heartache 101 ~Sour into Sweet~ is a free game for Windows only. Download it here, or have a look around the site at content other users have created.