There is nothing worse than staring at a games menu screen or first level and having absolutely no idea what to do. Usability testing allows the developers to figure out the strengths and weaknesses of their design, be it poor level layout, bad documentation or difficult gameplay. Getting people you have no connection with to help analyze the project is more beneficial than getting a close friend to try it out. A true stranger will explain just how something is, rather than a close friend saying its the next work of art or AAA indie game when actually they are confused to the overall meaning. Planning realistic goals for usability tests is probably the best goal to strive for. Small, calculated steps in determining what can be improved will be easier to maintain and implement. Clearly stating the controls of the game before hand is something I plan on doing because as of now, the players have to guess as to how my game is controlled.