It has overlapping plot in the same way Overwatch does. Technically the characters all have backgrounds, and that's what Arcane shows some of. The game may use that to give character to the heroes, but the game itself doesn't really add anything to it. The game is probably improved by the existence of the show (I assume, I never cared for it I'm general), but the show really doesn't depend on the game.

(Technically I think there are multiple games in this universe now. I can't tell you much more, but I think there's an action game with some pirate character at least. That may have more story, but it doesn't matter for Arcane.)

After all, you and me baby? Ain't nothin' but mammals.

It assumes the BoS ending from fallout 4 because the airship is named the same and power armor jetpacks.

Lol, no, thats just the big one that raises some questions about the timeline, if you think the Fallout show properly follows even the lore of F4 you're not paying attention.

Just off the top of my head right now while I shit:

• Ghouls don't take drugs to not turn feral

• Where the FUCK is the NCR, the country? It wasn't just Shady Sands surrounded by ruined LA, it was an actual nation-state that had civilization and laws and was generally less shitty than the rest of the wasteland

• Mr. House was NOT at some pre-war meeting where Vault-Tec admitted to their vault tests AND that they'd drop the bomb. If he was his actions as explain in FNV no longer add up.

• for that matter, that vault-tec meeting scene at ALL

• No, the Enclave are NOT still around with enough power to still have scientists and camps and shit, we've destroyed how many of their HQs now?

I could go on if I thought about it but its wipe time