Personally I'm fine with just, straight up roleplaying an MMO without deep ties per say. Find it a bit fun, though it will mean a good bit of quest idea generation on the GM's end if we move toward a more casual type of deal. Especially since quests could be turned down. It just needs more depth, an options which is going to be quite a big ask.
I think a real challenge will be the fact there's going to be a "IRL" aspect to this.
Whether it be just a timeskip, or if the player's get to interact in the real world outside of the game.
That may be something to consider soon, since they do have lives outside of the game. Also after playing a dungeon twice or two dungeons, seems like a good cool off/get away from the computer time unless one has a vast amount of free time and dedication for gaming alone.
Another point would be... loot. I would probably recommend finding a loot table of some sort for ye.
Outside of the "artifact", I don't think any other items were specified from the boss. Just that there were items available for all of our classes and races. But.. what were those items and what play styles do they go toward? What do they look like? What are the upsides/downsides of it, and maybe why to pick it over other items or current items?
What stats do they boost, do they grant any passives, or additional skills, etc?
Really, really begging on this part, or at least a semi-description. As otherwise it feels a bit, empty.
Especially in MMOs where different gear effects the build of a character, and the game play style along with creating a need for loot hunting/collecting & selling.
Since it seems everyone respawned in town immediately, I'm going to assume that the chance of items being taken from PK'd is only if the item is out in the open.
Also, not all loot has to be good as a heads up, varying it is acceptable remember that. It can also be parts of armor sets that give bonuses for having a full set equipped, or just look cool. Ye can drop an armor piece, but not the full set, or just a weapon, that might be semi-okay, or be useful as scrap or sale. Junk items that are worth in game money are a thing too (paintings, idols, jewelry that may be crafted to do stuff, components, etc.)
A way to keep the party together (without the jester) may be walking into a dungeon and procking a hidden event campaign could also be a thing (where the players have to have a main group together to continue the plot) likely granting a chance at rare items, or at worst locking the party from going to other dungeons until the story quest is complete.
It seems you really want the party to head after the Jester, but at the moment there is far more reasons not to.
As mentioned, some of the persons here minus jaiden since he does work in cybersecurity but would risk being banned don't really have a decent chance to stand up to the guy or away to achieve it which is why Jaiden wanted to avoid conflict with them earlier. The motivation for going after the Jester is a little low.
A simple solution I would see to tie them together would be blackmailing the doxxed players.
Perhaps giving a list of demands, which does force the group to generally stay together, in turn Jaiden receiving an online "bounty" on the guy. The alternative of Doxxing Jaiden would be less likely, and may have his job actively ban him from playing said game in turn for a full investigation
Or corrupting/threatening to corrupt character ID's...
Depending the Jester could be pissed off that they may have not received the artifact, or at least a fully functional one.
As Goibniu's automaton could have damaged or even broken it, which I don't think was noticed. Leading to the Jester needing to manipulate or otherwise hunt down the party again, whilst being looked out for, or needing to manipulate a situation to buy or trade the artifact indirectly from the party. If they try to trade it, they would need to bring something to the table and possibly reveal more of their own motivations.
It'd probably be less invasive to have the Jester be a background or reoccurring threat otherwise. Such as them paying other players to PK the party, and thus making dealing with Jester (or their midway guy) more pertinent. But that's more of a tightrope (don't want to overdo it), because... as a player, that could raise the chances of just, quitting tbh. So it'd have to be annoying but not overwhelming, probably more of a villain of the week type of deal.