Dolmenwood, as a variant of Old-School Essentials - which in turn is a retroclone of B/X D&D - is chock-a-block full of procedures:
- The game identifies a "Basic Game Procedure" (Player's Book, pp. 138-139) which resembles what's discussed by Umbran and Willie the Duck. I've included a screen capture of the outline of this procedure. It also greatly resembles the three-step basic procedure of D&D 5e (2014 PHB 6 or 2024 PHB 8).
- The game has a daily travel procedure (PB 156-157).
- The game has a distinct camping procedure (PB 158-159).
- The game has a distinct daily "spend time in town" procedure (PB 160-161).
- The game has a dungeon exploration procedure (PB 162-163).
- The game also has procedures for encounters (PB 164-165) and combat (PB 166-167).
I would contrast these with the rules detailed on pp. 144-145 of the Player's Book, which I would take to count as
mechanics using the implicit definition/assumption in this thread.
Games with similar procedure-heavy gameplay would be the OSR-influenced
Errant or the OSR-and-4e-influenced
Trespasser.
To take a pass at differentiating between
mechanics and
procedures, I would say that mechanics
can be elementary or fundamental, but don't have to be, while procedures
can't.
When I refer to game mechanics being capable of being elementary or fundamental, I have in mind fundamental particles; that is, a mechanic is elementary if it is unable to be broken down into self-contained, fully-functional mechanics. For instance, making an attack in D&D 5e, as detailed in 2014 PHB 194, strikes me as elementary or fundamental: its constituent steps can't be resolved individually when shorn from the context of making an attack - at first glance, at least. (
Edit to add: Those constituent steps can be used as part of other mechanics, such as rolling an ability check, but they don't work individually as mechanics themselves.)
To my mind, then, a procedure of play cannot be elementary; it will necessarily invoke more elementary or fundamental mechanics. For instance, the combat procedure in Dolmenwood invokes the mechanics for making attacks, which can function effectively even outside of the context of combat. (
Edit to add
The downtime rules for Xanathar's might also be a procedure, since they invoke the mechanics of rolling ability checks.
Edit to add:
As an example of a
mechanic that isn't elementary, I'd suggest casting a spell in D&D 5e. You might make an attack roll, or the spell's targets might roll saving throws, or neither; you might expend a spell slot, or not; and you might cast the spell by using a mechanically-defined unit of "combat time activity" - actions, bonus actions, or reactions.
Also, one other way I'd distinguish procedures from mechanics is that you can use a single procedure to constitute an entire gameplay session, but not a mechanic, as such. For instance, a WotC-era D&D combat could easily last an entire hour or hour and a half (or longer!), and one can spend an entire three or four-hour game session just exploring a dungeon (using either the less-structured "basic play procedure" from Dolmenwood or 5e, or a more-structured procedure, such as in Dolmenwood, Errant, or Trespasser), but, you wouldn't, say, make a single attack roll and call it a day.