Is there a specific PbtA rule book or something I should get my hands on?
Since PbtA is only a "rules-variant" there is no specific rule book, but if you like Post-Apocalypse you can check out the one that started it all: Apocalypse World (V2 seen in my image - though the difference between V1 and V2 is supposed to be minor).
If you like High-Fantasy, like in DnD, Dungeon World might also be a thing for you.
how would you recommend one get started?
If you're coming from DnD starting with PbtA is actually a bit more difficult, than if you're completely new. Having played DnD before brings a bit of baggage: You mentioned already, that it's way different – narratively influenced by the fiction; in contrast to DnD. Especially the Moves-structure is always a bit of a struggle for former DnD players, playing Pbt, in my experience.
My recommendation would be to either be a player in a PbtA Oneshot game (or alternatively watch a game on YouTube), and then read the rules, especially focusing on the GM parts, to see how the GM in the game you played/watched, did what they did.
Another important advice: Do not plan too much ahead! Maybe just have some two or three rough ideas for what could happen, e.g.:
- Metro 2033 – The group's food is running low. What are they going to do?
- Mad Max – The party is being harassed by a gang of brutal motorcyclists.
- Fallout – Radiation somehow got into the group's vault, so they have to leave it for the first time …
And playing to find out what happens from there, improvising what would be interesting, factoring in how the players roll.
That is of course if you want to be the GM. If you want to be a player: Just get a GM who knows their stuff. As a player PbtA is very easy to learn (which is why my recommendation is to first play a game of PbtA).
Yeah, I probably would want to start as a player and not a GM. I've only done DnD a couple times so I don't think it would have too much influence on my ability to learn this. With my lack of knowledge in it I'd definitely want to get comfortable as a player before ever committing to being a GM.
Thanks for the info! Youtube always has a wealth of knowledge so I'll start there and dig in a bit to see what I can find. Thanks for the help! Cheers.