The other day I reflected on what I'd change in my megadungeon, or consider changing, if I re-did it with what I know now after running 30 sessions in it.
Here are things I'd do differently from a rules/play perspective. Some of these I've discussed before, but this is the latest-and-greatest and tries to pull them together. I didn't list things that I changed along the way, because you can always assume that I'd have changed it earlier (such as how some spells work, say, or the duration on Shape Stone) if I could. These are things I don't think I can just go back and change without some grave damage to the game as currently going.
Uniform Enchantment Costs
I'd set all enchantments to a uniform cost. No more smoothed casting costs for Quick & Dirty enchantments at $1/point, Slow & Sure at $20. I'd just set all of it to $20/point. Even a lowly Fortify +1 spell would cost $1000 on a full suit of armor.
This would make the better non-magical armor and weapon enhancements a much better deal.
Gameworld Coupled Enchantment Maxima
I'd couple armor and weapon enchantments to the value of the underlying weapon in some way. Probably the "one enchantment or enchantment level per prefix" approach.
More Loot From Day One
I'd have put in more money from day one, since for a while delving was like a minimum wage job - you could get by on it, if someone else paid your bills for you. Not good for delving. I fixed this later, but it really was a mistake I should have fixed way earlier than I did.
I like my 250 coins to the pound game, but man, it would have been fun to have 50 coins to the pound for the same value, so big hauls of treasure were a serious weight consideration.
I'd have incorporated at least parts of TG from the start, so we could have learned its ins and outs by grappling with monsters.
Now, admittedly, it came out well after my game launched, but I did have my playtester copy and access to Doug, who'd certainly have been happy to have an ongoing playtest the whole time he was finishing the book up. Still, some of the way this was meant to be a game we played for a while until we got bored meant we tossed a lot of stuff to the curb. It's only now it's clear how useful this would be as a basis of grappling in a game where the monsters are ridiculously strong and the heroes very powerful.
Revised Talent Costs
I would use the talent costs from Power-Ups 3 instead of the costs from Basic Set. For the Barbarian and Scout, especially, this saves some real points.
I'd give these a harder look, although I might make them a bit narrower. Not "Knight" or "Barbarian" but "Melee Weapons" and "Missile Weapons" or things like that. Ones that made broadly skilled (but not crazily broadly skilled) guys a little easier to do and hold their ground a bit better against specialists. And if not Wildcard skills, I'd look at Talents to cover these.
More Characters Per Player
It would have been really interesting to have required people to make up both a 250-point and a 125-point character, and either play one or the other each session. Build in a backup, so to speak. DF15 wasn't quite ready to go during the planning stages of the game, though, but it would have been nice to start the idea of a pool of characters off as a standard, with differently ranked guys so we could mix in power levels. I'm not sure how this would have worked, but at least half of my group has played in my old pirate game where we had multiple PCs per player and different point levels for each of them. I'd also let them make up some hirelings themselves and throw them in as findable NPCs (and I may still do that.) It would have been fun to try!
I'd also consider Vryce's player's argument that Sacrificial Parry is way too good regardless of cost, and either ban it outright or more strongly limit it - perhaps say it counts as more than one parry for multiple parry purposes.
To be honest, there are a couple more things I'd do but that I'm in the process of addressing (and hope to get into Pyramid Magazine) so I can't write them out here. But they have to do a bit with combat and loot, if that helps any.