Piano Tiles was a game that I developed for a real time operating systems class. It is written in C, uses UCOSII and runs on a NIOSII processor programmed onto the DE2-115 FPGA. We were taught how to use the FPGA and OS in class assignments and labs, but the idea for the project was left up to the discretion of the student.
https://github.com/benhaub/School/tree/master/Piano%20Tiles
Note that the BSP folder is only included for completeness. The code I wrote is in the scr folder