I was thinking about special abilities RPG characters have, and how their use is often limited by a set resource pool, whether spells per day or a pool of points, like Champions's Endurance. One thing I've seen a lot of in video games, but not in RPGs, is limiting an ability's use by making the character build up to a certain point before activating it.

This would change the flow of conflicts, at the least. With resource-limited abilities, the best strategy is usually to lead with the strongest powers, to do the most the quickest. Sometimes you may wait a bit to make sure you actually need to expend those resources, but once the decision is made, it's beast to act as quickly as possible, before the party loses any more hit points.

Building up to activate special abilities would require a different strategy, one that prioritizes "filling the special meter" over maximum individual attack damage.

Needless to say, this would require a fairly stylized combat system, and one in which fights typically cup for several rounds, to give birth sides time to charge up their special abilities.

This could create some teamwork opportunities too. Maybe creating a certain effect requires abilities from different classes, races, martial arts schools, or other types of characters, so the PCs would have to coordinate to access their most powerful abilities.

Depending upon how complex you wanted the system to be, you could have a mix of resource-limited abilities which are used to charge or activate more powerful special abilities.

I think as ideal implementation would integrate opponents' actions into the flow, so that the PCs aren't just trying to get the same predictable 3 move combo off every time.

The old White Wolf Street Fighter RPG used combos, but the later moves in the combo were just normal moves with a speed bonus, and the combos were built during character creation. It was "neato" for a little while, but got repetitive and overly time consuming once the new wore off.

There are really two ways to approach this, and they are not mutually exclusive: chains or combinations of specific moves executed over time, and "filling the special meter."

You could, for example, have individual special powers that could be activated by using some or all of the "special meter," and much more impressive team abilities that require multiple team members with full "special meters" to coordinate their actions.

Although this concept mostly comes out of fighting video games, there is no reason it should be limited to combat in RPGs. A social version of this could be used in a political campaign, a nonviolent magical version could be used in a game focusing on mages and magical research or such ... basically any extended conflict or scenario that the game focuses on could use a mechanic like this.