Note 1: This is a thread about game design and preferences. The point is to talk about the different ways that different RPGs resolve situations.
Note 2: "Favorite" in the subject line can also be interpreted as "preferred" and might come from a game you WISH existed. Again, the point here is to talk about how things get done in play, as enabled by the rules and the mechanics of the game.
The Scenario: the classic "party heist" where one character is on over watch from a removed location, a stealthy character is meant to search for The Thing inside, while the face character keeps the Villain busy, with the Heavy uncomfortably shoved into a suit and ready for inevitable violence. Note that the genre does not matter: it could be cyberpunk, fantasy or modern espionage or anything else, as long as the structure and archetypes make sense.
How does your favorite game do this? How does it deal with nearly every character in the group essentially separated doing their own thing simultaneously? How do the rules interact with one character watching from afar and being the comms hub? How does it keep the Heavy engaged until violence starts? How does stealth work? Social interaction? What about being discovered by the guards or enemies or whatever? What happens if one character enters combat or conflict but the others don't?
If your favorite game can't really manage this sort of situation, why? Would you modify that system, or seek a game that isn't your favorite but does this better? Or would you simply not use this situation in play?
So I’ll use AD&D 2e for my answers (it’s probably my second favorite edition, but I feel like 5e has been kinda talked to death or at least more people have a sense of how it’d work.)
2e really doesn’t handle this elegantly as part of the system - it relies on the DM to adjudicate, and leans more on the “trust your DM” side of things, which I will admit can be painful if your DM is a 16 year old kid (as I was when I was first playing with my friends.)
Since our setting is generic D&D fantasy, the “comms” would have to be done magically with the wizard or cleric using a telepathy or sending spell (the latter probably via scrolls or magic item due to it being a 5th level spell). The limitation of how often you could use it might be interesting because it’d be more for emergencies than constant comms. Thieves could possibly use thieves cant and hand signals from across the room but all the characters would need to be fairly close by due to distance constraints.
The heavy would largely be working with reaction rolls based on their interactions, and it’d largely be a true role playing exercise, with the DM determining how the NPCs interact. We often used spot bonuses, meaning if the idea seemed plausible, the DM could give the player a plus or minus on the roll. So if the heavy is trying to intimidate some foppish noble at a party, they may get a +4 to their reaction roll if they’re trying to use their intimidating stature against the seemingly weak and unsuspecting NPC.
Stealth was always tricky. Typically, the only characters that could hide in shadows or move silently were thieves, but we always said any character could try to hide but they had to describe how they were doing so. Thieves simply could do so in extreme situations, meaning they had chances to succeed with their abilities even when it was impossible for a non-thief to do so. This might mean rolling for whether an NPC heard a noise or was surprised. Hear Noise was probably the best metric for determining if an NPC noticed someone, even if the name seemed like this would just be an auditory factor. We played kind of loose with this.
We always ruled that if combat began, all players were technically in combat and more importantly in initiative, though verbal and non-combat actions typically went first. Since the party is split, it would be on the DM to keep things moving very very quickly, and I’d try to bring the combat to a close quickly, or bring the party together.
Clearly, the system is very free form because it doesn’t have obvious rules for handling this stuff and so it may or may not be how every table would handle it, nor would it be for every group.