Mari0 is a free and open source indie game that combines Super Mario Bros. and Portal style gameplay.
The game was released last week and since then it has already received 4 updates that fixed several game issues and improved overall performance. Plus there is a new DLC pack as well that you can download from game options.
So if you haven't tried the game yet, give it a shot now. Instructions remain same for Ubuntu.
Download game from here, extract the archive and run the commands below to add Love2D unstable PPA:
sudo apt-get update
sudo apt-get install love-unstable
Now run the command below to launch the game (mari0_1.4.love will be in your game folder):
love-unstable (path to mari0_1.4.love)
Check out a nice gameplay video made by Northernlion: