Not everyone downloads and plays the game on the same day and when you start the game, there is no reminder, warning, or disclaimer that shows to hit x on the title screen.
Clicking doesn't work. Hitting space bar, escape, or E didn't work. Hitting all the other keys on the keyboard didn't work. My instant thought was that the game was broken and that should never ever be the first impression for any game.
Just askin for small text at the corner of the title screen that says "press x to continue". That's not difficult nor unreasonable.