PCs not getting along

[Quertus]

There were some violations of DBAD involved, and some players never get it until they get a bucket of cold water splashed in their face. The first approach is OOC "why are you being a back stabber to party members?"

Another viable solution is for the other players to kill off the gnome PC. By doing this, the other players send that player a message: no, you aren't funny and no, we are not putting up with this. And we mean it.

Is this particular situation only solvable by that means? I don't think so. The OOC 'same page' approach is a best path forward at the moment.
If he pulls this kind of crap again after an OOC discussion, lay the lumber on his PC to clearly spell out consequences for violating DBAD.

Hopefully, the OOC discussions will render the above approach moot: but in some cases, players need a wake up call delivered by a (figurative) maul to the head.

But, again, it wasn't the Gnome who initiated PvP, it was the GM. So don't kill off the Gnome, kill off the GM, get someone else to run the game. That level of (verbal) clue-by-four might serve as an adequate wakeup call to everyone involved, no?

[Psyren]

But, again, it wasn't the Gnome who initiated PvP, it was the GM. So don't kill off the Gnome, kill off the GM, get someone else to run the game. That level of (verbal) clue-by-four might serve as an adequate wakeup call to everyone involved, no?

I believe OP is the GM in question and might object somewhat to being killed

[Kardwill]

But, again, it wasn't the Gnome who initiated PvP, it was the GM.

The GM set up a PVP scenario without first talking about it with his players (which is a common mistake. I'm fairly sure I did it myself some times), and the Gnome player escalated it (which is something that happens fairly often in my experience. Many players will get overenthusiastic in this kind of situation, do "something that sounds cool" and not really think about the consequences until it's too late).

Since the GM admits in the OP that he may have made a mistake, and since it was the first time the gnome player did something that outrageous (the GM sounds surprised that it happened, so it's unlikely such screwups are common occurences) I don't think a "punitive" approach against either of them is the solution.

OOC discution in person (not by e-mail! IME, tempers tend to flare more easily in written conversations) is the way to go. Admit that what happened wasn't cool, and discuss how the table wants to go forward : retcon, change the characters so that they can have a new group with new dynamics, or decide how they want their characters to get together (and on friendly terms?) again. "Continue the game with a PVP focus" sounds like a bad plan with an inexperienced GM and already angry players

[kyoryu]

The GM set up a PVP scenario without first talking about it with his players (which is a common mistake. I'm fairly sure I did it myself some times), and the Gnome player escalated it (which is something that happens fairly often in my experience. Many players will get overenthusiastic in this kind of situation, do "something that sounds cool" and not really think about the consequences until it's too late).

Since the GM admits in the OP that he may have made a mistake, and since it was the first time the gnome player did something that outrageous (the GM sounds surprised that it happened, so it's unlikely such screwups are common occurences) I don't think a "punitive" approach against either of them is the solution.

OOC discution in person (not by e-mail! IME, tempers tend to flare more easily in written conversations) is the way to go. Admit that what happened wasn't cool, and discuss how the table wants to go forward : retcon, change the characters so that they can have a new group with new dynamics, or decide how they want their characters to get together (and on friendly terms?) again. "Continue the game with a PVP focus" sounds like a bad plan with an inexperienced GM and already angry players

Honestly I go back to my four options... and the one everyone seems to not notice - retcon the session. "Whoops, guys, I screwed up. I set up the situation badly. Let me redo that and let's start over, okay?"

[Quertus]

I believe OP is the GM in question and might object somewhat to being killed

Touché.

Honestly I go back to my four options... and the one everyone seems to not notice - retcon the session. "Whoops, guys, I screwed up. I set up the situation badly. Let me redo that and let's start over, okay?"

"The Gnome, having just scored two completely different artifacts from somewhere else entirely (work with player to determine type and source) meets with his old friends over drinks. {Gnome}'So, I hear you got a promotion. Sorry I couldn't be there. What's the new job like?' (work with player to detail promotion) {Orc}'And the crazy thing is, at the ceremony,' (work with player to detail conversation with changeling) {Changeling}'And you're just in time, we were about to leave to (work with players to build adventure hook) - care to get the band back together again, and join us, just like old times?' "

Act like a good version of the retcon session already happened? Or too crazy?

[KorvinStarmast]

The GM set up a PVP scenario without first talking about it with his players (which is a common mistake. I'm fairly sure I did it myself some times), and the Gnome player escalated it (which is something that happens fairly often in my experience.

The Gnome players is complicit, and is part of the problem.

@Kyoryu: the retcon is certainly an option as a GM initiative.