Ok, first you need either mari0-source.zip or mari0-linux.zip but not both. They basically contain the same things.
So, in your zip you have file named mari0.love . It's the game.
But to run it you need the game engine Löve 0.8.0 . These instructions were to install 0.9.0 . Mari0 don't work with 0.9.0, it just work with 0.8.0 .
First, remove the ppa (Which contains 0.9.0) by typing "sudo ppa-purge ppa:bartbes/love-unstable" then "sudo apt-get update".
To install Löve 0.8.0, just search "love" in the ubuntu software center, or type "sudo apt-get install love" in your terminal.
Then, once it's installed, double click on the mari0.love file you downloaded earlier. And the game should work.