Ok, I’ve thought about this idea some more, and I’ve come up with the following.

Each character has a personal quest, some sort of long-term goal that he/she can work toward over the course of the campaign. It doesn’t have to take the whole campaign, but it should be long-term enough that it should last at least until the next tier of play. Now, these personal quests to not grant experience points directly; they may inform adventures that I come up with and reward the whole party XP in an indirect way, but they do not grant XP to a single character, leaving the other characters behind. Instead, any time you accomplish some significant goal that gets you closer to your ultimate goal, you get one or more story points.

Story points can be used to do a variety of things, both story-related and mechanical, and their capabilities and limitations are largely up to a specific gaming group. I’d like to give my PCs a lot of narrative control without having to use story points, so they’ll be affecting the story in a lot of ways without having to spend these. However, they might be able to use story points to:

• Change an NPC’s disposition toward them. The PC would have to come up with an explanation for this; maybe the NPC is secretly attracted to a PC, or maybe they knew each other a while back and the NPC just remembered this.
• Dictate some loot that will make it into the adventure in the near future, probably in the next session. If there’s a particular magic item that a PC reall, really wants, this is a surefire way to get it soon. It does, however, have to be level-appropriate. I’d also probably say that, if the PC is willing to spend a lot of story points on it, it doesn’t have to be deducted from the party’s treasure parcels for the current level, but it can be if the PC doesn’t want to spend a lot of story points.
• Automatically succeed on a single skill check. Great for skill challenges, not being surprised, etc. This, again, will require narration and explanation.
• Turn a regular hit into a critical hit. This use of a story point would likely be limited to once per encounter, or perhaps every time you use it in the same encounter, it doubles in cost. This would be a nice way to get some mileage out of feats that only trigger on a crit; my PCs tend to avoid those, because you might never get a chance to use them.

Those are just some examples. Another thing about story points is that I’d like to encourage players not to hoard them by giving them an expiration date, similar to action points. My idea is that they can carry a limited number of story points over into the next adventure: 1 at heroic tier, 2 at paragon, and 3 at epic. Any story points above that are lost.

Now, I’m really curious about what other people think of this mechanic, so feedback is welcomed.