So we were finishing up a dungeon adventure a few weeks ago and one kid says, "We should do a Harry Potter game!" Shouts of "Yes!" and "I get to be Hermione!"
So I set myself a goal of one week to modify the DungeonTeller rules for a game of adolescent hijinks at a magical boarding school. If you don't like the HP books, then go watch the finale of Breaking Bad or some Sunday Night Football. Otherwise, keep reading.
I didn't want the young players fighting over who gets to play whom from the books, so I decided to set the game 20 years after the last book, when the children of the main characters are themselves heading off to school on that damned train. Unlike in real life, the kids get to choose their parents: one decided to be the daughter of HP and GW, the other of RW and HG. So I guess they're cousins.
In terms of stats, I came up with four key ones: Courage, Wit, Heart, and Power, which correspond to the four houses (Gryf, Ravenc., Hufflep., and Slyth). You have six points to spend, but you have to put at least three points into one stat to ensure you get assigned to that house. Both players chose Courage and ended up in Gryf. I think it would be a good idea from the outset to canvass the players to find out which house the PCs are going to belong to. Wonder what a Slytherin campaign would be like?
For actions, I did a modified dungeonteller action list:
Fly (on a broomstick)
Each player could choose a pet/familiar for their PC that gives them a +1/+1 bonus to a couple of actions. A cat, for example, gives you +1 Notice/+1 Sneak when it's with you.
The spell list had to be just right, because I'm running the game for a couple of experts. Fortunately, the HP wiki has the spell lists done by year learned and all I had to do was sort them into the seven spell types: charms, curses, hexes, jinxes, and so on. Each spell type requires a different pair of stats/actions for the number of dice you roll. To cast a charm, for example, you get to roll your Incant dice plus your Talk dice, whereas for a transfiguration spell it's Incant + Wit.
Characters in HP are often tired out from studying/practicing. The health system in the game gives you checkboxes in five descending states of health: refreshed (+1 die to checks), okay (+0), tired (-1), knackered (-2), and out cold (ZZZ). I created a cool mechanic where the LOWER you set your default health state, the MORE "practice points" you get to add to individual spells that you've been studying. So if you're Hermione-level studious, you are knackered all the time but you may be a whiz (or a which) with your favorite spells.
For spell duel/combat, the caster rolls to cast the spell and then needs to make an Aim roll vs. the target's Dodge to actually hit. It worked pretty well. One player used Wingardium Leviosa to raise the other's robes over her head, and she countered with an Aguamenti jet of water to the aggressor's face. We haven't had any serious combat yet.
We did a Quidditch game with lots of Fly, Dodge, Notice, and Aim, and Sneak rolls as needed. It was in a narrative style and not strictly play by play until the crucial moment when one player (her team's Seeker) had to race the other Seeker to the snitch while avoiding bludgers aimed at her by the beaters.
At the end of the game session they got to add an action die to one action of their choice but ONLY if they had used that action in-game.
As for the plot, it centered around them befriending an orphan who was another first-year. They figured out that she had been sneaking out at night and with some clever skulduggery tracked the girl to the mirror of Erised, where she had seen a vision of her mother. What the players don't know is that the girl's mother was BELLATRIX LESTRANGE and her dad, YOU-KNOW-WHO, and Bellatrix's spirit is waiting to possess the girl as the first step to returning to power.
There was also a potion-ingredient hunt involving butterscotch, hippogriff feathers, and mandrake, and a visit with a certain gigantic groundskeeper to help him brood and hatch a pegasus egg.
We can't wait to continue the story and I'll share more after the next session.