Sunday, May 06, 2012

The Pool Burning Mechanic

Burning a pool for an advantage is a very common mechanic. You can find it everywhere, this idea of spending from a limited pool of resources for a power-up.

For example, in Street Fighter you can use a super move if you spend part of your super bar. In FPS games, weapons with more limited ammo (pools) are more powerful than those with plenty of ammo. In oldschool D&D, your magicians burned spell slots to cast spells.

This mechanic needs to be carefully considered. Normally it is a supporting mechanic rather than a primary one. The reasons are easy to explain: it's the old "quadratic wizards" problem.

See, in D&D a wizard was useless unless he burned up a spell. Low level wizards had a very small pool, so unless the party was going to rest for eight hours every five minutes, the low level wizard was going to spend most of his time useless. However, as the wizard gains levels, he gains spell pool slots, and the whole pool always regenerates at the same speed. Eventually, the regeneration rate matches and then outpaces the burn rate, and you have a quadratic wizard that can burn pool in literally every encounter.

Similarly, an FPS with plenty of ammo, players can spend it like water and not worry about running out.

In a tabletop game, pools usually regenerate very slowly and are prized as resources you absolutely don't want to spend. Hit points are a pool. Health potions in your sack are a pool. Wands of lightning have a limited pool of shots. But if the players get very powerful, these pools become very easy to refill or switch out - someone with eight lightning wands will just go ahead and spam them against everything.

So, the heart of a pool burning mechanic is trying to balance the rate of burn and the rate of regeneration. If you make the pool burning mechanic a core mechanic, you're going to raise the rate of burn exponentially. Can you create a method of regeneration which matches that without regenerating so fast it makes spending pool essentially free?

Let's pretend we have a game where the players have several pools of resources they can burn, and that's their primary mechanic. However, the pool regeneration is slower the more of the pool they have spent.

This is a positive feedback cycle, and is generally an extremely bad call. In a multiplayer game, having the players that do better able to do more better while the players that are struggling have an even harder time... that's generally going to end up with a few gloating munchkins going "man, we have to stop to let you regenerate again?"

On the other hand, you could make it so that the pools regenerate at a specific rate, but if you're low, you can actually go out and refill them using some mechanic that produces role playing. For example, a heroic character might have to help someone to get a rapid pool recharge. A magician might have to uncover secrets that the bearers don't want revealed. You can even make the regeneration system so that the players have to help each other to regenerate pool, which would be fun.

By making the regeneration a core motivation rather than a core limit, you can make the game many times deeper.

Still, at heart, if the game is primarily about choosing how much of which pool to burn, you're going to have a very... fast game. That kind of mechanic isn't very amenable to long confrontations over dozens of turns. Instead, you're likely to have fewer, shorter confrontations. If you want your game to have few confrontations per adventure arc, that's fine.

But if you want to allow more conflicts, you need to either A) radically enhance the pool rules to allow for tons of give and take over the course of a fight or B) come up with another set of core rules to allow the players to act without every action being a worrying choice.

B) is, of course, the path to making your pool burning rules into support rules instead of core rules...

Anyway, that's my thoughts on that.


Keto said...

I believe it depends upon the sort of story you want to tell and the sort of pacing you want for encounters.

For a game like D&D, I don't believe the system works very well. You have a limited rate of output and a rapidly growing pool of power. It really is the same as giving players a gun with limited ammunition, and that does not work very well considering the type of adventure D&D represents.

My solution to this is to take advantage of the mechanic and use it to pace gameplay and simplify encounters.

Regeneration time can be very long term and conflicts very short. Rather than a story aimed at the level of 'he kicked you, then you blocked, then you counterattacked with a sweep' it becomes an encounter of 'he surrounded you in flames and your wind was not strong enough to blow it out, what are you going to do about it?'

Will you reach into your reserves of strength and attempt to overpower him, even if it cripples you later? Will you be burned heavily and run? Will you attempt to negotiate? What will you do about this fact that he wanted this situation more and should beat you in a direct contest.

This, first of all, means that direct conflicts with powerful being are very costly. Both of you probably don't want to get in a fight, because even the winner might be crippled.

Likewise, because your pools run deep, you almost always have farther in your pocket to reach if your back is against the wall.

Wounds can be healed at a faster rate by exposing yourself to 'your element' so these wounds don't even represent rates, but how inconvenient it is for you to recover.

In short, I believe that the pool mechanic does discourage frequent dangerous conflict, but also that it can be balanced just by ensuring that your pools and ability to regenerate them remain relatively constant. You expand characters mostly in base power, outside the pool.

Craig Perko said...

Yeah, that's exactly what I mean.

Personally, I think that's the wrong call. I think it's very low-traction. I prefer a game where the players can make a larger number of lower-risk choices and attempts.

But that's preference, and you are obviously free to go the opposite direction.

Keto said...

Well, it isn't though the bulk of the player's power is through this system.

A player could be capable of - fighting competently with a sword, telling a decent story, telling a convincing lie, setting a block on fire, and doubling the productivity of a local factory - all without blowing wounds.

It is just that they can't trivially do major things. Otherwise, wouldn't those major tasks lose meaning?

Craig Perko said...

Sorry, I didn't catch that from your first message.

If you're only using pool burning as a minor part of the game, it's hard to mess it up. The question simply becomes whether burning pool is a relatively minor, common boost or a rare super.

Again, I'm in favor of "minor and common". I really like the give-and-take, piece-by-piece progression players can make when the system allows for small amounts of headway with each choice.

Random_Phobosis said...

Regeneration by roleplaying reminds me of Fate-based RPGs. Restoring energy for roleplaying disadvantages is the best virtue/flaw system I've seen so far. I'd say, "major and common".

The downside is that Fate family is pretty low-traction in terms of game mechanics.