I've been very busy writing #HIVELIFE1979 so my time spent here on my blog has really dried up, but there's something I wanted to post for both you and for me. Whilst I don't think there's an absolute formula for a successful 'scripted' adventure - I know if I can get what I write to do the following things, its going to work on a primal 'reason to be engaged and get some closure' level. It's just a skeleton, if the meat on the bones is shit, then the whole experience will leave a bad taste - but if you pack loads of imaginative and fun things that happen and the players can do, you're onto a winner.
It follows a basic scriptwriting technique of 8 steps (or key scenes)
1 - Status Quo & Inciting Incident - The world is shown to the players and they're told where they fit into it. Something happens that propels them to step 2
2 - Predicament & Lock In - The thing that happened at the end of the last scene now leaves the players with a problem or conflict they have to sort out. Their first step towards this goal puts them on a path they cant easily get off.
3 - First Obstacle & Raising the stakes - The characters must overcome the first step towards their goal this could be a medium sized dungeon or wilderness/urban area, also a number of options or resources should be taken away from them.
4 - First Culmination - The reason options have been removed in step 3 should be resolved, and it should be a harder task than they tackled before. Tone is important here, it should mirror the tone of the desired outcome and overall adventure.
5 - Subplot & Raising the stakes - The players will thank you for a little distraction, not too far off course but something thats not directly pivotal to the main plot, but is connected somehow. A great place to weave in some setting or story exposition. Continue to remove options or resources.
6 - Main Culmination - This is where the players deal with the final threat, the BBEG or whatever. They think they're done, this should mirror the vibe going on in step 4. Also you could give them some inkling its not quite over.
7 - New Tension and/or Twist - Everyone loves an encore, or facing the puppet master - the players should figure it all out and deal with that shit here.
8 - Resolution - They all live happily ever after, or do they? This doesn't even need to be played (although its fun to do it, but make it quick) just wrap up the events of the game with a short and concise 'read aloud box' if you want - players wont feel cheated as they should have had the satisfying ending of step 7.
Some further advice I've been thinking about. Some people will tell you scripted adventures are shit as you've got a railroad for the players to run on. I don't think thats the case if you do a couple of things. Plan what the bad guys are going to do - and plan what happens if the players don't stop them. The rest you make up at the table.