In Linux Mint, what do I do to fix dependency problems?

I installed a game (The Witcher 2: Assassin of Kings - Enhanced Edition) from a .sh file, and whenever I try to open it, a launcher with the game image launches, but when I click "Launch Game" or "Options", a little window called xmessage pops up. -Its contents are pasted below; I installed the game onto its own partition (I intended to install all my games onto a seprate partition) if that means anything;

Here (right desktop screen):