Following some very kind advice from the Old School Wargamers* on running a participation game, I've been thinking rather on scenario design.
My preliminary thoughts (dreamt up while lying insomniac abed whilst trying to get over my jet-lag!) are these:
One idea I have found really helpful in approaching the scenario is to use Victory Points. I'm working toward the idea that the first side to hit a certain number of VPs wins the game. It seems to be a useful way of allowing me to introduce some tension for the players - a tension between means and goals.
To illustrate, I am thinking that one party, the defender, is going to have one main goal and that is to retreat over a bridge, blow it and sail off happily into the sunset. That's his main goal; if he manages that he wins the game... provided he also picks up a subsidiary goal as well that I need to think about as evilly as I may.
Anyway, to this end he's going to have to hold out against roughly 2:1 odds (that's very roughly) whilst a party of pioneers prepares the bridge for demolition. They'll be successful from move "x" on on either the roll of a value on a d6 or the draw of an event card. The spanner in the works for him may well be that as a random event, the Colonels' daughter Miffy may well decide that it's a lovely day for a trip into the countryside. Naturally Miffy's capture will be a major (say 40-60%) flow of VPs to the attacking side.
Likewise, his position will be open to a flanking movement that might put enemies in a position where they can attack the defenders' pioneers and make the destruction of the bridge difficult/impossible. This will also present the difficulty to the defender of having to detatch a sufficiently large force to defend the pioneers. Perhaps the destruction of part of the pioneers will delay the happy moment when the bridge might be blown.
As to the attackers, I want a tension between having to recklessly attack on the one hand and the knowlege that each figure lost gives the defender VPs. I think this will be created by the knowlege that any move after move "X" could yield the event card that says that "Yes, the bridge is ready for demolition". I like event cards!
Likewise, Miffy is a rich source of VPs, but is the risk of snatching her worth the expenditure of soldiers when a determined attack on the defenders at the bridge might end the game at a stroke?
That's about where I am at the moment.
*You know who you are!