I'm tinkering with a framework to implement board games in c# (similar to boardgame.io in JS) part of that is getting a handle on turn structures. (What is a round? what is a turn? who gets to go when? etc)

So I've gone through all my games and looked for recurring patterns and exceptions to them and here's what I've collected so far:

• There's always at least one structure that handles how player act or "take turns"
  • the vast majority of games do traditional turns - one player does things, then then another,
    • usually in a fixed order maybe going forward some times and backward other times.
    • sometimes the order can change
    • also possible are:
      • turn order decks (you don't know who goes next but know that everyone gets a turn)
      • action tracks (where whoever is furthest back gets to go next, possibly resulting in an uneven number of turns)
      • the next player is dependent on an action of the previous player
  • it's also possible that players can play simultaneously
    • a complete free for all is pretty common
    • it's also possible that players can act freely to some point, then have to wait for everyone else to catch up
  • another consideration, both for concurrent and sequential play is that sometimes some players are excluded (Codenames for example lets all guessers on a given team act concurrently but not the leaders or the other team)
  • there can be different rules at different times (like first picking a tile in sequence then everyone can place it simultaneously)
  • and there can be nested rules (like every player gets to run an auction but in every auction each player get's to bid as well)
  • one relatively common special case is where certain actions on a player's turn result in decisions being needed from other players (trades, attacks, "each player ..." effects)
• there are often structures that simply subdivide another structure
  • they can occur at any level. A game may be divided into "setup" and "play", a round could be divided into different phases but a single player's turn might also be divided into smaller steps.
  • these subdivision usually restrict / specify which actions are allowed in them
  • these subdivision often come with limits like: you can only do N actions
  • sometimes a player can "pass" sometimes they cannot

I'm wondering if anyone can think of an instance that is not covered by these "rules".