Well blow me, I won.
Now I just have to deliver the goods!
Adventure in a Nutshell: The adventure itself is the race, made up of an interlinked series of encounters along the route: including sabotage, traps, ambushes and other underhanded and sneaky obstacles, as well as the terrain and daily life of the city itself getting in the way. The intended theme would almost be that of a car chase in a modern cop show, complete with exploding melons, cardboard boxes and chicken cages getting devastated en route. The adventurers may spring their own traps and obstacles for the other racers, and the various Skill and Ability checks—as well as the conditions and the route taken—add or subtract to the time taken to try and claim the prize.
The various encounters interlock with each other in a similar fashion to the old Choose Your Own Adventure books and could, conceivably, be run through by a single player. Failing to jump a roof-gap in one encounter, for example, might drop you down into an encounter on a ground route.
The final goal of the competition is the guardhouse atop the gate on the opposite side of the city, but the door is locked and the climax is a death-defying climb to deliver the letter and claim the prize. A failure in this could lead to a nasty fall, especially with other competitors trying to push you off, pouring oil over the stones, or otherwise doing things to get in the way.
The city treasury may have put up the prize for a reason. A proven, capable and ruthless messenger may be just what they need to take a letter or item securely, safely and swiftly from their city to another. What the package is may not be clear, but it may well be important enough for other people to pursue. With that as a hook, this adventure may act as a springboard to other adventures and a way to get the adventurers in the good graces of the ruling powers in several cities.