Try the new version :) - it's the same res but should open in full screen.
Ahhh didn't think to change my screen resolution, I like big chunky icons and such so had set lower. Just played through the game though aaand that was fun. Once I worked out I could jump on stuff as it falls I felt like Quicksilver in one the slow-mo Xmen scenes or Legolas in The Hobbit haha. Good stuff.