We playtested the StarWorm mechanic last night with Volant, and it didn't go well. It wasn't because the mechanic didn't work, which was as expected, nor that the players didn't grok it, which surprised me. They had no problem handling it.. That all went fine. It went roughly because I was having a tough time setting the stakes properly. The key is, as we hashed out after the game, to make the neutral position - which is all dangers bought off, but no opportunities gained - what the PC wants to do. I kept setting the stakes wrong, with no good neutral stake in play. This made things awkward and difficult. It worked well the two times I set the stakes properly, but not when I didn't.
Other problems were as expected. The two most immersive players, who visualize everything in their heads, had some trouble backing to a slightly less immersive stance to handle the stake setting. Klax suggested it would play better with minis and a grid, which surprised me, but made sense. The shifting between task and conflict resolution, and the use of the stakes to avoid rolling for the opposition, all worked swimmingly.
We decided to try again next week. Hopefully, I can learn from my mistakes, and bring the awesome I know is in this mechanic!