Hi! I wanted to share some thoughts I've been having recently about the role of Oracles in role-playing game design, in both GM-ed and GM-less games. It's my view that oracles have two main uses: introduce the unexpected and disclaim decisions.
Before we begin, it's probably helpful for me to lay out what I mean by "oracle." Here I mean any sort of randomization mechanic that players consult to divine results. Dice rolls and card draws are the most common oracles, but drawing stones from bags, spinners, and even Jenga towers can be oracles.
To give a broad case study of games and their relationships to oracles, I'll be looking at The Quiet Year by Avery Alder, Blades in the Dark by John Harper, Kingdom 2e by Ben Robbins, and TODO.
Disclaiming Decision Making
Players of "traditional" RPGs like D&D in its various forms will recognize oracles that disclaim decisions. When a DM in D&D 5e asks a player to make a History check, they are saying "I want to disclaim the decision as to whether or not you know this fact." The die roll takes the question out of the DM's hands to some extent (though they're still setting the difficulty of the check). Blades in the Dark takes this a step further by codifying a Fortune Roll into its rules; the GM may assemble a die pool to answer any question they find interesting, as they see fit. Neither of these rules truly make the GM into a neutral arbiter; they can choose when, why, and how to make the rolls. I would argue that it is the appearance of neutrality that's important; the die roll smooths over TODO.
Often GMed games will only present GM-facing rules to use decision-making oracles, but that doesn't mean other players can't get in on the fun. While I've never seen it included in a game text, some players will use dice to break ties in their own decision-making process ("on an even number I sneak past, on an odd I go loud"). TODO
Most GM-less games feature no mechanics to separate players from their decisions, perhaps because they're more collaborative by nature. For example, Microscope and Kingdom have essentially no randomness at all, other than what the players themselves bring to the table. One exception I discuss later in the post, but I'd be curious if anyone can come up with any others.
Introducing the Unexpected
Oracles that introduce the unexpected are, as far as I can tell, more common in GM-less games. The Quiet Year and For the Queen both feature a deck of prompt cards players draw from to move the fiction forward. For example, a player drawing the 2 of Diamonds in The Quiet Year must either answer "Someone new arrives. Who? Why are they in distress" or "Someone leaves the community. Who? What are they looking for?" It's entirely possible that the current player was waiting for just this prompt and has a great idea tailored for the moment; it's just as likely that they're caught off guard and have to think for a moment. Both are effective ways of using the randomness of the prompts to spark interesting directions of play.
My only example of this oracle in GM-ed games is random content tables, very popular in the OSR. No one, not even the GM, necessarily knows what will happen; the dice and the table together introduce some unexpected element as the next step in play. Spark tables in Electric Bastionland are explicitly intended for this purpose: take some prompts and produce something interesting from their friction.
None of this is to say that neutrality-laundering and interesting prompts have to be mutually exclusive. Sleepaway asks one player to decide the actions of the lurking Lindworm, which is stalking the campers. Each time, everyone closes their eyes except the one player who secretly draws three cards and chooses one as the Lindworm's course of action. Their choice is constrained by the playing cards they draw and the prompts in the book (like "The uncanny, Alien Sensations, Floating Bones"), but they do make the final choice of which to place and which to discard.