Some thoughts on game balance, from a recent article by Adam Robert Thomas:
In general, video games strive for a sense of balance in terms of difficulty. The game needs to be challenging enough that the player is engaged and feels like they’re struggling with a sense of danger that provides tension, yet it also needs to not be so hard that they become frustrated and walk away. This is of course represented in what developer’s like to call difficulty curves.
— The Golden(Eye) Rule of Enemy Design! by Adam Robert Thomas
