I've mostly played D&D in the past, and thus have ample experience with character advancement that is primarily based on increasing power: higher level characters pack a bigger punch (especially when it comes to magic). For example, fireball deals more damage and affects more creatures than burning hands. For the most part, however, characters are in complete control of their abilities at all times; the fireball goes where you want it to go.
However, recently I've been wondering about what it would look like if character advancement was primarily about control, not power. At lower levels you can whip out the same fireball spell, dealing the same damage, as you can at higher levels, but you have more trouble putting it where you want it and minimizing collateral damage.
There are obviously a huge number of implications to the game based on this sort of change to character advancement, so I think it would be a non-trivial task to take a power-primary system and make it a control-primary one. So I'm curious, are there any published systems out there that have played with this dynamic? I don't currently have a group to try this out on, so I'm just looking for something to read to inform my speculation at this point.
