I like this a lot. It turns the skill challenge from a dry dice-rolling exercise to something that has presence in the world. It seems like you should still use the mechanics from RC to balance the challenge, but this format to give it verisimilitude.
One criticism: with all the cross-references, the format seems like it might be hard to understand for even moderately complex challenges. Here's a rewrite of your example that tries to solve that problem by focusing on PC actions more than the sequence of events:
Breaking into the Vault
Moderate Level 10 Skill Challenge (DC 18)
Read aloud text:
The giants' vault is protected by a massive iron door. It's about 12 feet tall and 10 feet wide. Unfortunately, the ceiling above you seems to have been damaged in the battle and appears ready to fall.
Challenge Overview:
There are three problems for the heroes to overcome: the door, the ceiling, and the approaching enemies.
The door contains an obvious lock and a hidden trap. If the door is unlocked or attacked without disabling the trap, the trap triggers.
The ceiling above the door is damaged and will collapse in two rounds.
The enemies will discover the heroes in six rounds. If the trap is triggered, an alarm will sound that could cause them to arrive sooner. If the heroes get into the vault before the enemies arrive, they can lock the enemies outside.
Ideal solution: 6 successes
- Examine the door to discover the trap
- Study the rune
- Carve the counter-rune
- Pick the lock
- Open the door (x2)
Events
- End of second round: Ceiling collapses. See "The Ceiling," below.
- End of sixth round: Enemies arrive. See "The Enemies," below.
Information Gathering:
History (DC 18) recalls the giants' traditional vault-making methods. Success makes DCs easy (13); failure gives wrong information, making DCs hard (26).
Dungeoneering (DC 18) examines the vault design and improves methods. Success makes DCs easy (13); failure gives wrong information, making DCs hard (26).
Religion (DC 18) recalls the giants' superstition about broccoli. (The trap will do half damage to anyone who has eaten broccoli during this encounter.)
The Door:
A massive iron door 12 feet tall and 10 feet wide with an obvious lock.
Examining the door (Perception DC 18) reveals the trap: an intricate rune carved at the top of the door.
Picking the lock (Thievery DC 18) triggers the trap unless it's been disabled.
Attacking the door (100 hit points, resist 10 all) triggers the trap unless it's been disabled.
Opening the door (Athletics DC 18 x2, requires lock to be picked) takes brute strength; it's a heavy door, seeing as it's a giant's vault.
The Trap
The trap is hidden. It can be discovered by examining the door (above). If the trap is triggered, the following occurs:
- Trap explodes. Close blast 5; +20 vs. Reflex; 8d6 fire damage, half damage to anyone who has eaten broccoli during this encounter.
- Alarm goes off. The enemies arrive in 3 rounds.
- Secondary lock activates. Requires Thievery DC 26 to open.
Studying the rune (Arcana or Thievery DC 18) reveals that it's a fireball trap that can be disabled by carving a counter-rune on the opposite side of the door.
Carving the counter-rune (Arcana or Thievery DC 18, requires the rune to be studied) disables the trap.
The Ceiling
The ceiling is damaged and will collapse at the end of the second round. When it collapses, the following occurs:
- The ceiling falls. Close burst 5, +20 vs. Reflex; 5d8 damage.
- Work becomes more difficult. Chocking dust fills the air and rubble and masonry block the door. All remaining skill checks take a -2 penalty.
Examining the ceiling (Perception or Dungeoneering DC 18) reveals when it will collapse and what will happen.
Shoring up the ceiling (Dungeoneering DC 18 x2) prevents it from collapsing.
The Enemies
The enemies arrive at the end of the sixth round. See combat encounter, pXX.