When you create a Game Loop where progression is gradually delivered to the player after certain conditions are met, we create a pacing. The pacing will determine how patient, skillful, lucky, or a combination of all; a player has to be in order to get to the next step.
Naturally, our players will get better, accumulate more power and have more options the more of the game they already unlocked, so to keep the challenge interesting we also gradually increase the difficulty or cost of these conditions, thus pacing is usually incremental.
When you set what content is given based on the challenge level a player confronts, you are creating a Game Economy. In essence, this is at the heart of what Economy Designers do!