Going Full Rogue

When I started running 4e, I very nearly had an all-rogue group. During session 0, I expressed some concern about everyone being the same class, due to the importance of combat roles in that edition. The discussion eventually led to a more diverse group. I kind of regret steering them away from it, as in hindsight, I realize it could've made for great fun, and would have force me to think outside the usual "heroic campaign" mentality with which I usually approach storytelling.

Agreed on the importance of a detailed city map for this sort of campaign. I think I might get a little bored with humanoid opponents, too, as there's not much room for monsters in a city. That said, creativity is really the biggest limiting factor in making such opponents as diverse as anything you might pluck from the Monstrous Manual.

I read this post a while back and recently it has started to really seem like a fun idea that I want to utilize. I was thinking to either tell everyone they have to be a rouge or let them take a multi-class of rouge and one other class starting off. Would this be difficult? I have not multi-classed myself before and definitely have not done it in 5th edition. I like this idea more just because it will likely give more variety to the characters' skill sets. Some examples could be rouge/ranger(marksman), rouge/wizard(mage hand/illusions), rouge/fighter(the muscle), rouge/bard(sleep spell/cone of silence etc.), rouge/monk(ninja?), rouge/cleric(trickery as previously mentioned), and well you could argue for any class but these are the ones that make the most sense(forgot to mention sorcerer and warlock).

Plot wise I was thinking that the party are all recruits for a thieves(and maybe also doubles as an assassin's guild) guild. They would start out doing pretty simple missions but would slowly evolve to become some of the best thieves in the guild. They would then be sent on dangerous missions, such as, big heists, political missions(one senator wants another senator imprisoned so you have to plant evidence etc.), and maybe even some assassinations. I want to avoid a huge conflict focus and keep the plot more story and RP driven because my players often get bored with combat and also tend to take a long time to take their turns.

What do you guys think? I am especially curious on your thoughts about multiclassing(especially starting off) vs. all rouges. The main reason I prefer the multi-classing option is that there are only 3 rouge archetypes and this would result in duplicates in a 4 or more person game. Also, how difficult is multi-classing, I am generally pretty patient about this kind of stuff but some of my players have trouble keeping track of their skills etc., will this overwhelm them? Also, if someone wanted to should I let them just start as a level 2 rouge or does this not compensate for the other players multiclassing?

Also, after rereading friartook's initial post I realized we had a lot of the same ideas. Now I'm wondering about his idea of creating additional archetypes, it would be a way to give variety, however, how would I go about this in a fair way?

You can play a their gang and not all be rogues.
Rogue: pickpocket/cat burglar/safe cracker
Bard: con man/face
Fighter: Security, extortion, mugging

My whole idea for this campaign was a heist campaign. Heists, political intrigue and gang wars.

The "all rogue" aspect was my starting point for this. I realize(d) that a more balanced/normal class makeup could participate in such a campaign. But I have always loved rogues in general, and I thought an all rogue campaign/party would be a fun time!

I'd say that bard and trickster domain cleric would be fair game in my campaign, but otherwise I'd want the party to be mostly rogues.

Not everyone likes playing rogues though. If my DM said I had to play a rogue..I'd walk tbh.

If the players were into the notion it'd certainly be something to try. I particularly like the idea of a ninja clan in an oriental setting. I've been waiting to try out some L5R ever since I got my hands on the 3.0 "Oriental Adventures" book when it was still new. Perhaps more so than with rogues though, ninjas could, indeed should, be specialized into different roles. That could mean some aren't rogues, but could also mean there's some multiclassing or homebrew solutions at work. There might be some custom magic items that temporarily lend class features from other classes. Or "disposable" constructs that could tank for an encounter and then fall apart.