I would love for Rock, Paper, Scissors to come back, but I do have 1 addition / thought.
In the new context of "competitive co-op", I think Rock, Paper, Scissor would work fine for "Contentious Coop" (like DOS 1), but if you REALLY disagree, or even were not part of the conversation/decision making, on your own you could talk to the person and follow choose a different dialogue and consequence path with them.
Example.
Players A, B, C, D
Choices 1, 2, 3, 4
A, B, C (together)
A selects 3
B selects 1
C selects 4
(do some type of rock, paper, scissors like you described, maybe the conversation leader (A) gets a bonus point for talking first, given the disadvantage again them if B and C disagree all together)
Result: Let's say that B wins.
Player D later talks to the same person, the NPC might do one of the following:
- If NPC doesn't know or care that Player D is with others, does dialogue options again, this could cause D to go off on a completely separate mission, potentially in contest against A, B, C.
- If NPC does care, he has different dialogue options, which D will have to convince NPC to do a different path (persuasion, intimidation, or what not)
- D steals from, provokes, or kills the NPC - which might potentially ruin quest/options for A, B, C, but whatever that's how it goes. This gives ability for A, B, C to either back up or go against D.
Also maybe Player C is not happy with going along with Player B choices, so C instead talks to NPC separately to convince them of something else, or joins D, or does any of the options D could've done described above. This could lead to A, B vs C, D - or even A, B vs C vs D in a 3 way battle/competitive quest or what not.