kalirion: I don't consider Borderlands series to be anything close to a "pure" FPS. The enemies, especially the elites, get ridiculously bullet spongey unless you keep up with having top gear for the level. I'm talking being able to tank like 50 headshots from a sniper rifle that's just a bit out of date.
amok: if you have mobs that needs "50 headshots from a sniper rifle", then you are playing it wrong... anyway, bulletsponges exists in 'pure' FPS's also, at least in Borderlands you can do something about it. and I never said it was a 'pure' FPS anyway, but the 'purest' of the hybrids.
There some FPSs which have RPG elements that aren't strong enough to be considered hybrids I guess - Painkiller, Shadow Warrior reboot, Hard Reset. And I read that Shadow Warrior 2 became even more like Borderlands.