OpenLabyrinth is an open-source (GNU-GPL3 license) 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 3.3 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 3.3 is very stable and recommended for production settings. Version 3.4.1 has a number of more advanced features but is harder to install and is more fussy about PHP version and other factors. Apart from maintenance fixes, we will not be continuing to develop OpenLabyrinth v3. All our future efforts are being directed towards OLab4 -- https://github.com/olab/OLab4
If you want to see some of the latest development features, send us a note via http://openlabyrinth.ca/free-trial/ and we can set you up with a test account on the demo server at http://demo.openlabyrinth.ca/