Dusk is pretty great. I don't know why I never played through it when it came out, but I finally played it now.
It starts off a bit like a Quake clone - a very slick and polished Quake clone but a clone nevertheless - but it doesn't stay that way. The feel of the game really changes as you get further into it, and it feels more inspired by the atmosphere of immersive sims like Thief and System Shock, and occasionally horror games like Amnesia. The level design has clearly learned some tricks from Half Life and Portal, and plays with verticality and sense of scale quite a lot. Above it all, the game feels almost like an exercise in narration that uses old-school FPS mechanics but is much more about what it makes you feel. Considering that the developer has a history of making atmospheric horror games, I'm not surprised.
Don't let the low-fi primitive graphics fool you, there is nothing primitive about this game.
Oh, and of course it has a movement system. Simplified, not quite full-on Quakeworld/CPM but at least it's there.
Highly recommended.