Cocos2d-x was recently added as a supported platform, but there are a lot of others as well! Support for Tizen has been announced for a number of products, including Yoyo Games GameMaker: Studio, Appcelerator Titanium 3.0, Project Anarchy from Havok, and many others as well.
Tizen wiki has a useful, community-supported list of alternate ways you can be developing or porting Tizen apps. While not all of the environments listed on Tizen wiki are fully supported today, it's a great place to look for inspiration and to see if your favorite application framework has been added, or if support is in the works.
There are a lot of great options out there for creating an eye-catching app. We're looking forward to seeing what you create!