About eight months ago I got the chance to run a game and this was the one I pitched. I began trying to pull together strands of all the things I had laying about to make it into something fun. Since I was going to use a heavily modified 3rd edition rule set the Harry Potter feel was tossed out the window - kids tossing around spells meant for dungeon diving didn't fit. I developed the school into a collegiate form with the PCs sharing the same adviser. The adviser assigns a group project where the PCs are to write a report on each of the Seven Secret Crafts per term.
The campaign outline was basically for there to be an adventure based around each of the Secret Crafts. This would take the first seven terms and ten terms would be needed to graduate. However their instructor was Troikithus, an Alphatian spy, who was using the PCs to gather information to report back to the Empire. He would be murdered at the beginning of the eighth term and things would escalate until war was declared on their graduation day - campaign over.
Things didn't go as planned. At all. And I'm about to just end the damn thing so we cam play Dresden Files instead.
Things That WorkedMy natural ability to adapt. That's it.
Things that Didn't WorkThe Spell System
Since everyone was a wizard I used rules where you could cast any spell you knew of the appropriate level as many times as you wanted. However you had to succeed a caster to check to do so. The idea was that since there was no limit on what they could cast, knowing more spells made you more powerful so a major goal would be to learn new spells. I even created spellbooks for each player and printed out one page descriptions for each spell they knew so that they didn't have to look them up (and also because some spells needed editing and there would be lots of unique new spells.)
The problem was that every time they failed at casting a spell their fun diminished. On top of that they never really got into the whole "collect spells" things. I should have just made it so that they didn't have to roll to cast since they were under utilizing what they could do anyways so there wouldn't be any problems with being too powerful. In addition the big spellbook required them to spend a little extra time to become familiar with what was in it and no one had the time or inclination to spend an extra second thinking about the game outside of the session (or sometimes in the session.)
While I had a structured campaign in mind my natural instinct to just let players explore was too strong. Except for the few Secret Crafts people wanted to join no one gave a damn about their assignment. I probably didn't push it enough, either. So they wandered off aimlessly in their own directions and the campaign took this rambling, directionless feel. Players with more drive dominated play while others fell asleep waiting to be pulled in. I eventually grabbed the reigns and began forcing a story on them but it just felt wrong and nobody really seemed to care at that point anyways.
Additionally I think the use of the d20 rules made everyone think this was going to be an actual Dungeons and Dragons game. They kept wanting to find things to kill when I was trying to make it a more socially oriented, school focused game. There was a place for action and adventure but it wasn't supposed to be in some dungeon. Unfortunately I gave in to those instincts and the school and social stories fell into the background.
The Session Length
The group I'm in does short campaign runs. I figured ten sessions, one for each term, and a few more thrown in here and there as needed and I'd be done. However, even when I got to run the initial adventures I had prepared, they took at least two sessions to get through. This was due to the player's unfamiliarity with my houseruled system, my allowing people to explore as they pleased and that we usually had 2 1/2 to 3 hours of play in an evening. As it stands, we're eight months in, on session 12 and there are still four terms left.
Wrong Game for the Wrong Group
There are lots of other things that went wrong, but what it really boils down to is that it was the wrong game for the wrong group. What the game eventually became probably would have been fine with my old D&D groups - they loved detail oriented, crunchy campaigns that could potentially go on forever. But this group is usually exhausted by the time they get to play so lots of fiddly details and crunch are pretty unwelcome. They just want to have fun, not go through college all over again. Additionally the campaign structure that I ended up with was one that did not lend itself to resolution in a reasonable time. Plot threads are hanging all over the place and if I had another year or more to run the game they would all be covered. But I don't have that long. Better to just put a pillow over over its face and move on.
What Would Have Been Better
I should have just run this as straight D&D with all spell casters as was one of my original visions. The Great School would have been as originally written with the PCs just sharing a master and having more free time to adventure and poke around. No terms, no structure, just adventuring until they reach level 5 and graduate.
The other option would have been to use a different system but I'm not sure what would have worked without jettisoning details about spell casting. The main feature of D&D for this game was the lists of existing spells that works so well to give wizards that "nose in the books" feel. Perhaps Ars Magica would have worked.
So, it's dead. If I'm allowed behind the screen for this group again I'll probably run something like Dungeonworld, a Gumshoe game or Lady Blackbird.