We had a chance to delve some of the Vault of the Goblin last night with friends from college who we haven't gamed with in about 15 years. It was a blast! They played a group of four level 4s (two elf champions, a dwarf myrmidon and a human fighter) along with my human cleric 3 (who was REALLY needed) and broke up the activities of the Cult of the Dragon behind a mirror that Mary's character had previously discovered but had not yet explored. I made a few discoveries in the process...
1. The minimal rules serve well. At some point, rules begin to, by their nature, minimize options. They become more about what you cannot do in a situation than what you can. To whit: the fellowship met a banshee early on. I am going with the B/X banshee that is the remains of an elf maiden. We had already established that Mary's character is a member of the elf nobility - so she asked if she knew who this elf was, and if she could speak with her. She made a few good rolls, and before long had made a positive connection, and the banshee really wanted to be helpful - willing to tell the fellowship all she could. However, I had no idea that they'd ask to pick up her body (which the banshee was still connected to), carry it around, and use the banshee as a portable auto-kill machine. I set a chance each turn that the banshee went all crazy on them and turned full banshee, but it never happened. They kept motoring through the complex - well after they had exhausted all of their healing, spells and extra resources - and kept letting the banshee wipe out their foes. The big fight - with a 6 HD hydra - ended quick when it failed its save. The other big fight, against an 8 HD salamander and his tribe of troglodytes, ended much more quickly when the banshee took out all but one of the trogs.
As the session wore on, my friend razzed me in good humor about how they had messed up my plans. I wasn't quite sure what he meant, but as I thought about it, I realized a key difference in my approach to adventure design today compared to me from 15 years ago... back then, I was a master railroad builder. I would write a story, and then decide where and how in that timeline the PCs fit in. The success or failure of the adventure, to my eyes, ended up being how well the PCs followed the script.
Yeah. I was that guy. I didn't even realize it until last night.
However, there was no plan. For each sub-section of the dungeon, I'm putting in a few factions with competing interests, putting in a few hooks for the fellowship to decide how to handle, and then letting the chips fall where they may as things go on. The fellowship could have infiltrated the cult from within, charmed the leader and had him write a new constitution for the cult turning them into a holy order of bee keepers, or tried to kill the leader, take his ring of serpent friendship, and try to ride the hydra like a six-headed steed while they took over the whole dungeon. It was all good with me.
In short, I like where the Vault of the Goblin is headed, and I think it's going to be a fun environment for others to play with once it's done. It's ending up very open-ended and dynamic.
Now, on to specific game stuff:
The decision to change the ability score range to 2-12 was met with some skepticism, but by the end of the night I think that they were converts. There were so many times that I had to ask for an ability check on the fly, and that was a great way to resolve the situation. The strong characters tended to have success doing things that strong people can do, and the weaker characters didn't. It plays very clean and intuitive. The difference between a 9 and 10 strength is a big deal in a lot of ways (5% chance to succeed on a check and +1 modifier) ...
In combat, they missed a LOT, but that was more a function of the dice rolling (which was almost uniformly bad - if not for the banshee, they would have suffered a TPK at some point, I'm confident - three troglodytes used up half of their resources in the first fight!), but I realized that the numbers are eventually going to scale out of control. In the draft I have going, you get to add your level (monsters add their HD) to all attack rolls. Since the game only scales to level 12 for PCs, a +12 bonus isn't too bad... until you do the math.
A fighter 12 gets +12 to hit. Fine. However, he also is going to be wearing something that increases his strength (I mean, he's a level 12 fighter) meaning that (conservatively) he has +3 from 14 strength and gauntlets of ogre power... and he is using a sword +3 (the best available in the game)... so now he is rolling 1d20 +18 to hit. So far, I like it - the bonus never scales past the die, making the die roll important...
Assuming that a foe will ever have AC that high. The same fighter is wearing plate +3 (total bonus +9) and carrying a shield +3 total bonus +4). Even a little bit of DEX gives him the max available bonus (+1) for that armor type, putting him at AC 10 (base) +9+4+1= AC 24. This means that he only needs a 6 on the die to hit a foe with maximum possible protection. Few monsters are going to have better than AC 25 - even at the highest levels.
I could scale this back considerably by only having the bonus tick every other level. Instead of adding your level to the attack roll, you add half your level (rounded up). At levels 1-2 (or 1-2 HD), you take +1 to hit; at level 3-4 (or 3-4 HD), you take +2 to hit... this drops my theoretical fighter 12's level bonus by 6 points, making his total attack modifier +12. This is MUCH more manageable. Now, against a moderately-armored foe (AC 18) he only needs a 6 on the die, and against a very well-armored foe (AC 22), he needs a 10 on the die. This keeps all of the numbers under control, and continues scale well enough - a 20 HD monster (just about the cap for this game as far as I can see - we're talking Tiamat here) gets +10 (base) to hit, although there will have to be some function for giving bonuses based on exceptional ability. I don't want to get into giving monsters ability scores (although that might be necessary with how much I use them... grrr) but that would allow the numbers to align better on the monster side of things. It's a little extra math, but having that information handy for monsters might be useful... something to ponder further.
One more thing and then I'll let you go (if you're read this far, good on you!) ... I realized that the character sheet is perfect EXCEPT for spells. I am going to create a second page only for those with spellbooks to use to record their spells and available slots. It's too much information, even for a level 4 caster, to fit on the front of the page in that little magic box. This way, only casters need to print out the second page of the character sheet - everyone else sticks with the one-pager.