LostSoul
Adventurer
Here's my attempt at it. I think this makes the PC goals and progress clear to them (by defining them in terms of tasks rather than "successes") and makes it very easy for the DM to run or expand upon as he wishes.
I like this one much better.
I don't think this situation requires a skill challenge. I think there are two in-game situations where skill challenges work well:
1. Abstract situations: where the situation is necessarily abstract - chasing someone through the twisting city streets of a massive megalopolis where mapping each street and what's in each building is impossible. Most social skill challenges are in this category. Successes needed represent the "stamina" or staying power of the opposition, and each success you get whittles that away.
2. Linear: a clearly-defined step 1 must be completed before you can proceed to a clearly-defined step 2, and the number of steps is the number of successes you need. Successes are clearly that - completing each step successfully.
This doesn't seem to fall into either category. This seems like a perfect place to use "parallel" skill checks.
[sblock=Parallel Skill Checks]This is how I do skill checks.
If each side is taking an active action, they have to make a check. The DC for this roll is determined by the opposing side's action; generally it's 10 + the opposing side's modifier.
When comparing the check to the DC, you get four results:
Disaster: check <= DC - 5
Failure: check < DC
Success: check => DC
Stunning success: check => DC + 5
Both sides make checks, so you end up with a matrix of 16 results. Some results seem like they'd cancel each other out. If you resolve the action taken with the check, they don't.
The PCs scan the crowd; the NPCs try to sneak their way in:
PC Success + NPC Success: The NPCs sneak in but the PCs have spotted them.
PC Stunning Success + NPC Stunning Success: The NPCs sneak in and are able to disperse, but the PCs have spotted them and know where they are heading.
PC Failure + NPC Failure: The PCs don't spot the NPCs, but the NPCs are unable to get into the city. The most boring one, but if the players don't know that they failed it could lead to interesting results.
PC Disaster + NPC Disaster: The PCs spot someone but it's a red herring; however, the NPCs are spotted by another guard and kept out of the city.
You can see how the situation will change dramatically based on the actions each side takes. There are many possible ways it could play out.[/sblock]