Is it trying to be cute through subversion? Like that one puzzle in Braid that nobody could figure out.
If not, then it's just bad design; press "Start" is as old as game themselves, no design pattern more deeply ingrained in players minds.
Aaah, I was ready to just close it and murmur that they didn't even test if the thing can be started on Ubuntu. That "start" totally looks like a button.
And after reading your comment I tried WASD first, which doesn't work.
