Here is a compiled version of the game for those who don't want to bother with compiling it.
Make sure you have java installed. For Windows you should just be able to double click on the
jar file.
There is also a DEB file that should install the whole thing along with a nice icon to launch it with a mouse.
The DEB file has only been tested on my computer under Ubuntu 16.04
If you're using linux make sure you use the Oracle JRE or the compiled OpenJDK binary provided by them.
On Ubuntu 14.04 and 16.04 the graphics don't render correctly at the screen edge with the OpenJDK from the repositories. On Ubuntu 18.04 the graphics render correctly using the OpenJDK from the repositories.
To run it from the terminal or command prompt type.
java -jar infinitetux.jar
for full screen type on Windows
java -cp .;infinitetux.jar com.mojang.mario.FullScreenFrameLauncher
for full screen on Linux and OSX
java -cp .:infinitetux.jar com.mojang.mario.FullScreenFrameLauncher