CreepTD on Ubuntu 14.04 (Linux)

Hey guys, I tried to install CTD on my Laptop, wich is only running with Ubuntu 14.04. When I try to open the CTD file, it only opens a text-document, in which it says, that jre 7 is missing, of which I'm 100% sure that its not. I understand, that oracle/sun stopped the support for linux, might it be, that CTD only runs with that?

Greetings,

Aaron