DUSK is one of those indie FPS that really nails the feel and look of the 90s, smooth and fast-paced gameplay, with a simple story and that relies mostly in skill, and not luck. If i have to define it, i would say it is a mix between DOOM and Quake, it contains the map scheme of DOOM (red, blue and yellow keycards), and the gameplay of Quake.
PROS:
Good retro graphics!, very customizable to suit your taste.
Excellent soundtrack, good mix of horror ambient and metal.
Very replayable, with an endless mode, (survival mode with hordes of enemies), and with many difficulties and secrets of each level.
Great controls and gameplay, bringing elements and physics never imagined in these kind of games, with lots of easter eggs.
CONS
Some physics are very weird, specially when jumping, it lacks the physic of jumping forward and "glide" down, (just jump forward and let go of w in the air). And the walls collisions are very exploitable thanks to bunny hop, but nothing to worry about.
The beginning is good but a little slow, but as a PRO DUSK is one of those games that the more time you spend on it, the more you like it.
Score: 9 / 10