I had trouble at first to get past the splash screen in audiosurf. If you have the same problem, this is the workaround I use everytime: When you launch audiosurf, a small white window will appear and the music will start playing. As soon as a fullscreen button appears, click on it immediately! (if two buttons appear, click on the higher one) Then, you will be able to click on the play menu option. The reason for this bug is that when you aren't using audiosurf in fullscreen, the mouse clicks are shifted (the program thinks you are clicking elsewhere on the screen) depending on the location of the window. So, whenever your audiosurf window gets shrinked (for example when you choose a song), you can resize it by going to the audiosurf video options and re-selecting your screen resolution. Good luck!
Note: it is also possible to manually edit the game config.ini and set fullscreen mode there
../..//../Steam/drive_c/Program Files/Steam/steamapps/common/audiosurf/config.ini
runfullscreen: true
