OpenLabyrinth is an open-source (GNU-GPL3 licence) platform for creating and playing virtual patients.
For more information about OpenLabyrinth generally, see http://openlabyrinth.ca
You do not need any software to play a case. Any modern web browser will work. If you want to try authoring your own cases, OpenLabryinth can be installed on a basic web server running Apache, MySQL, and PHP (eg a LAMP, WAMP setup etc.)
If you are comfortable using Git to clone, pull etc, this will work fine. For less experienced users, an alternative is to download version 3.1 as a zip file (see the Releases tab). Expand that zip file into a set of folders accessible to your Apache server.
The install routines are still a bit glitchy - we apologize for this. Linux experts should have no trouble. The rest of us mortals might have a hiccup or two.
Version 3.1 is very stable and recommended for production settings.
If you want to see some of the latest development features, send us a note via info AT openlabyrinth DOT ca and we can set you up with a test account at http://demo.openlabyrinth.ca/