By far the most difficult thing to implement in any game is balancing. If done right, you will spend over 50 percent of your development efforts testing, tweaking, retesting, and retweaking the game.

Don't use just one focus group to test your game, but use people from all walks of life. Have kids and public audiences, even your wife, husband, or partner to play your game, and gauge their feedback. The more number of people test your game, the better the balance of the game will be.

Finding that sweet spot between difficulty, playability, engagement, and fun is always hard, so do not underestimate it. Remember, just because you play the game in a certain way doesn't mean everyone else will play in the same way.