Back 4 Blood Supply Points and Certain Achievements Locked Behind Online Mode

Developer Turtle Rock Studios has locked achievements progression and supply points for Back 4 Blood behind the online mode.

Back 4 Blood: How To Unlock Skins - Corrosion Hour

River of Blood, Back 4 Blood Wiki

Back 4 Blood Guide: Best way to farm Supply Points — Too Much Gaming

STEPN Launches Badges & Achievements System

Back 4 Blood December 16 update: Nightmare nerfs, Ridden spawns, patch notes - Dexerto

Patch Notes

Back 4 Blood: Can you farm Supply Points solo in single-player? - GameRevolution

Patch Notes

Back 4 Blood Accessories Guide

Back 4 Blood dev discussing ways to address lack of progression in solo mode after player backlash

Trial of the Worm, Back 4 Blood Wiki