Get out of your comfort zone into the uncertain — this might get awkward.
Preparation
You need any small item as a game token and a dice that you can improvise to, like a 6-sided toy dice with images. Also pen and paper. (Check Variants if you have only numbered dice).
Note down 6 dice faces in a chosen order. It is the order of game stages and it doesn't matter for music apart from the last value which will indeed be at the very end the piece.
Setup
Agree on the starting player and the order of players to roll the dice (go clockwise if you are in the circle). This game intends to introduce a 'risk' of taking a very long time. For this effect to work well, it's best to reassure during the setup, that the attempt will be finalized 'no matter what'.
If so inclined, you may agree on details for musical interpetation of dice cues.
Put the progression marker on the first stage.
Gameplay instructions
On your turn, stop playing music and roll the dice. The ensemble changes the improvised music in accordance with the result. If the rolled value equals the one that is currently marked by the progression token, move the token to the next stage. Then (if it was not the last stage) this turn ends and the next player stops playing music and rolls, etc.
Every time the dice repeats itself try to include some differentiation in what you play.
Game end
The game ends when progression token is moved from the last stage off the list.
Gamemaster's note
The end condition of the game is the main mechanic to introduce the in-game tension as the duration of playing is highly uncertain. Most often players start rolling slow and then turns get faster and faster.
Game proposed by Adam Izaak Wasążnik. At Warsaw Music Games Meeting — it worked with a diverse group.
Variants
For a lighter version, you might not require the ordered progression. The game ends when all values appeared in play (so the ending part is not determined, but you also might happen to wait for it in length).
If you have only a numbered dice, get inspired by Diced Events activity and list the musical directions for events. You will need to invent your improvisational cues for this purpose and assign dice value to each of them.
If you want to make the game more difficult, notice that there are different types of dice, and some not uncommon go up even to 20 faces…
Trivia
Such probabilities were more generally considered in Coupon collector's problem (from as far back as at least 1708). For a lighter, non-ordered variant, expected number of throws is 14.7, the most probable value is 11 (although 10 and 12 are not far behind) and 13 is the first value where probability of the game being already ended is higher than 50%. The basic variant takes much longer on average.
Editor's note
Photo used for decoration is "New dice" by Yoshihide Nomura, CC BY-ND 2.0
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