When I first started making games, I was heavily investing my ego / emotions into my work. When things didn't "work" with a player, I would feel personally hurt. And sometimes, I'd be upset that someone "couldn't figure something out."
Believe in what you're creating. Believe in the heart of the project. Believe that you're taking a player on a journey. Know the core of the experience that you want to create.
Watch people play
Watch how they play the product. How do they interact with it? Are they having trouble with the interface? Are they delighted at times where you want them to be? Are they experiencing the emotional journey you want them to live? Watch their hands. Watch what's happening on the screen.
It is at this point where you have to LET GO of what you thought worked. You MUST listen to their emotions.
Billy Joe Cain started his game industry career at Origin Systems in 1992, and has participated in the creation of over 250 hit games for home game systems, mobile platforms, and PC / Mac, and has launched three game development studios in Austin, Texas. He believes that games are going to save the world through improving brain plasticity in adolescents as well as making education fun.