You can create Adventures in the early Lucas Arts style. The user can steer a character through rooms, talk to other characters and collect items. The items can be used on other items and so forth.
The framework also contains a road editor, which you can use to create little villages, where the user can drive by car.
Macao is a cross browser API. It works on Internet Explorer, Mozilla, Firefox, Opera 7+ and Netscape 7+. The framework is in stable beta stadium. You can try it out and get my support by email or via the Macao forum.
You can try the online demo and download the framework from:
http://macao.sourceforge.net