Rolling a 20
We've been conditioned to salivate when we roll a natural 20. It's very satisfying to crit on an attack roll, but on many other rolls, all we end up with is a regular success and a mouth full of saliva.
Whenever a natural 20 is just another success, I feel like it's a failure of the game system. Example: initiative rolls. I've frequently heard PCs complain when they crit on an initiative roll: "Why couldn't I save that 20 for when it mattered?"
I was once DMing for three players who each rolled a natural 20 on the same initiative roll. It was an astonishing one-in-8000 occurrence that, sadly, has no by-the-book game effects at all. I ruled that the players were so well-prepared for the combat that their opponents immediately surrendered. The PCs got full XP for the win. We still reminisce about that encounter.
D&D design principle: Natural 20 is magic. Every d20 roll - skills and initiative rolls as well as attack rolls - should have a benefit for rolling a natural 20: something more than just a success.
Rolling a 1 is the second most exciting roll in D&D. I don't know why it is, but it always gets groans and laughs. In every group I've ever played with, players narrate how badly they failed. "My axe gets caught in the floor!" "My Dungeoneering check was so bad, I don't even know I'm in a dungeon!"
Players are hungry for fumble mechanics!
Fumble rules are hard to write, though: there are a lot of pitfalls.
- Fumbles should introduce complications, not punishments: no permanently-broken weapons or missing the next turn. Fumbles should add player energy, not suck it out.
- Fumbles should not render all characters incompetent boobs. One of Rory's 3e DMs ruled that on every natural 1 on an attack roll, the character made an attack on an ally. Rory was playing a high-level ranger with many attacks per round. That meant that once every few rounds - several times a minute - Rory accidentally shot an ally. Not very Aragorn.
- Fumbles should be player-directed. Right now, players tend to exercise a little narrative creativity when they roll a 1. This is nice.
The natural-1 rules from the 4e Darksun books are pretty good fumble rules. They actually give characters a mechanical benefit - rerolling an attack - in exchange for a cinematic failure - breaking a weapon.
D&D design principle: Natural 1 is magic. Every d20 roll should have consequences for rolling a natural 1: consequences in addition to normal failure.
Do you guys use any cool fumble or crit effects for initiative rolls and skill checks? (Attack rolls and death saves already have special effects on a natural 20.)