I've come around to the view that the game having a set end, while not strictly necessary, will probably improve the game by focusing things on treasure hunting and avoiding the last few turns dragging out. However I'm also not terribly keen on anybody ever knowing for sure that they are on their final turn as this will inevitably colour their decisions. More uncertainty = more decisions and gambles = more fun.
So I'm proposing this to my game group:
Variable game length optional rules
We looked at the glittering pile of treasure just beyond the ruins to our left, we looked at the band of archers hunkered down in the building to our right, we looked at the ominous snow clouds forming thick and black on the horizon, then we turned our back on it all and headed for the warmth of home. Gold has little value unless you live to spend it.
The weather in Frostgrave is unpleasantly chilly at best and extremely hostile at worst. In a moment a blizzard can descend on an otherwise sunny day and all thoughts of treasure and fighting are swiftly forgotten in the rush for shelter and warmth. These rules are optional, but as they encourage a focus on treasure gathering over fighting, the lowest level wizard in the game should get the deciding vote if there is any disagreement over whether to use them or not.
Starting from the end of turn 5, at the end of every turn roll a dice. On a 1-10 conditions hold, play another turn as normal. On an 11-20 hostile weather closes in and the battlefield must be abandoned. Treasure left on the table at game end is lost. Treasure held by a figure still on the table at game end must be rolled for. On a 1-10 it is lost as the figure battles through the blizzard for shelter. On an 11-20 it is successfully recovered by the figure.
This means 50% of games end after turn 5.
75% of games have ended after turn 6.
88% of games have ended after turn 7, and so on.
I welcome any thoughts or feedback on the matter.