I imagine there's a few games to playtest at Conception: I'd like to playtest A Need To Kill; Iain will have Stitch, I imagine; Andrew will have Six Bullets; Rich will have his extensive range of Umlaut supplements ("Umlaut Rockbook: Glam!").
How would you feel about informally designating one slot, each day, as a playtest slot? Perhaps the evening. We could decide that there'll generally be a playtest going on each evening: there's no obligation to keep the evening free, but we'd make an effort to ensure everything got playtested.

