Borderlands 2 is damn near the perfect non-license Warhammer 40K title.
Everyone is insane. Everything is evil or hostile or relentlessly predatory. The few trustworthy people are still ruthless. Pandora itself is a seething, life-devouring ball of suck. What passes for authority is either grossly power mad and deranged or ad-hock and justified at gunpoint, and if the latter is "good" it's also highly likely to be destroyed by contact with any outside organization as a reward to maintaining order.
The Bandits are variously Human Scum and Orks, with Goliaths being Chaos Mutants.
The Guardians are Eldar -fast moving, shiny, delicate, and ent