After the game

Asking playtesters directly about their experience with your game or application will give you a lot more detailed information about why certain elements were good, and others will not give you so much. For example, one tester may like the Leaderboards because it gave them a sense of achievement, and the other may like them because they enjoyed being better than everyone else. These two varying opinions are useful; if your intention was to encourage competition, then at least you know that to some extent, it's working.

Asking them to explain the game to you

	"If you can't explain it simply, you don't understand it well enough."
	-- Albert Einstein

The same can be said about your game. If players can't describe what your game is about, or what it is supposed to achieve in its simplest form, then it's not clear enough. This could be because the rules are ill-defined or that the objectives are not clear enough. Perhaps your intention was to create a role-playing application to...