This is a game called Throwback Gorilla made for the GitHub Game Off. 

To play, just download the game and extract the zip with the "res" folder. Make sure the "res" folder is next to the jar and then just run the jar.

EDIT: I have added the file ThrowbackGorilla_java8_jar.zip for download. It should help people's problems with running the game throwing an error related to JNI