ETA: Just as a reminder, thus thread is not intended to be about how you,asGM,would run the scenario. It is about game system design.
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?
My weapon of chioce is Dungeon Carwl Classics, and it would handle this situation fine.
The character on watch would make the occasional Luck check (rolling their Luck score or lower on a d20) to notice anyone coming by. Alternately, I might call for an Intelligence check (with probably a DC 10 or so) if the character was taking specific actions that might warrant using that ability instead. These checks are contingent upon 1) there actually being something happening while the character is on watch, and 2) that happening not being revealed by other mechanics (such as an enemy blowing a roll trying to sneak up on the party).
The Face character could make a Personality check (again, probably at a DC of 10 or so) to keep the villain occupied/distracted, though I'd be open to a different kind of ability check or even a different apprach (such as a spell) depending on what exactly the character was doing. I don't like using dice to determine social interaction if I can avoid it, but generally if there's a chance of failure at any task I'll ask for a check of some kind unless success (or for that matter failure) is just too entertaining based on what the character was actually attempting.
The Heavy would be fine. No need for a check there.
The character searching for the Thing would make an Intelligence check or a Luck check, depending on which gave them better odds, unless the character was a Thief or Halfling, in which case they have pother abilities that might come into play. For that matter, a spoellcaster doing the searching could use their magic if they had something applicable.
In a low-level scenario I'd use side initiative, but if its a level 2 or higher situation I'd have a separate initiative roll for each character. Unless there was something causing a potential problem, the Heavy wouldn't need to do much of anything until the fight started, at which point they'd probably take center stage. I have characters get separated from each other on occasion, and it's never been an issue beyond making my job as a Judge more challenging.
DCC RAW doesn't do opposed checks, so a Thief (for example) makes a roll against a static DC to successfully sneak, climb a wall, pick a lock, whatever.