The Foothills is the first episode in DUSK. It features 11 levels (10 normal, 1 secret.). All the levels were mainly designed by the games creator, David Szymanski. Each level has a distinct setting but a shared theme across the episode, derelict farms or industrial areas, with the exception of E1M9 which is a city setting.
The main character, looking to explore the town of DUSK, PA, after hearing of the treasure kept within its ruins, is captured by cultists. He wakes up in a cellar, attached to meat hooks, with three chainsaw-wielding Leathernecks at the ready. A mysterious voice commands they "kill the intruder". From there on, he fight the cultists and makes his way through various rural locations, including farms, mines, and swamps, encountering The Intoxigator, and The Duke Brothers along the way. Finally he reaches the town of DUSK itself. The town is completely empty. The inhabitants are either dead, possessed or part of the cult. After entering a passage in one of the buildings blocked in the street - the main character enters a secret military complex, that houses The Experiments. After defeating them, he proceeds to The Grainary, and to Episode 2 - The Facilities.
An underground lair occupied by The Cult, under a farm and connected with the ruins of an unknown stone building.
Things: Fast Fire Totem 1
Enemies: Leatherneck 6, Mage 11, Black Philip 7, Possesed Rat 2
A small, derelict farm, complete with a barn, a corn field, a house and a neighboring forest.
Enemies: Leatherneck 14, Mage 21, Black Philip 23, Possesed Rat 5, Possesed Scarecrow 3
E1MS: The Dim Slough
A swamp that connects to a light sewer system and small factory. (The secret level of episode 1)
Enemies: Leatherneck 7, Mage 21, Black Philip 4, Possesed Rat 7, Possesed Scarecrow 4
E1M3: Old Time Religion
A overtaken church standing on a hill, leads to an underground complex of caverns, ruins and traps, leading to first Boss: The Intoxigator whose arena is in part of a sewer.
Enemies: Leatherneck 4, Mage 28, Black Philip 3, Possesed Rat 19, Possesed Scarecrow 4, Intoxigator 1
An old underground sewer complex, and pipe network.
Things: Enemies: Leatherneck 10 Mage 33 Possesed Rat 9 Possesed Scarecrow 3
A forest that connects to a mine, logging facility and blockaded railway system.
Things: Enemies: Leatherneck 7 Mage 19 Black Philip 24 Possesed Scarecrow 11 Fork Maiden 2
E1M6: The Cutty Mine
An abandoned (and allegedly haunted) mining complex, partially flooded, and caved in. The name Cutty Mine may be a reference to the 1998 game Thief.
Things: Enemies: Leatherneck 6 Mage 23 Fork Maiden 8
E1M7: Dead of the Night
A rather decently sized, and modern ranch. Home to the 'Sanctum of the Worthy'; the likely Cult HQ, and the Duke Brothers.
Things: Enemies: Leatherneck 18 Mage 41 Black Philip 7 Possesed Rat 2 Possesed Scarecrow 3 Fork Maiden 6 Duke Brothers 2
E1M8: Through the Gate
A mining zone and quarry that leads to the gates (and walls) of the town of DUSK.
Things: Enemies: Leatherneck 12 Mage 31 Black Philip 16 Possesed Rat 6 Possesed Scarecrow 10 Possesed Soldier 26 Fork Maiden 1
E1M9: Ghost Town
Inside a section of the town of Dusk, it is derelict, with many enemies that roam it, and a passage in the town leads to a dark secret...
Things: Enemies: Leatherneck 15 Mage 29 Possesed Rat 8 Possesed Scarecrow 2 Possesed Soldier 24 Fork Maiden 7
A secret military operation housing Living Experiments. It can be assumed that this site is extremely deep underground after seeing how hidden the experiments were.
Things: Enemies: Possesed Rat 2 Possesed Soldier 1 Scientist 2 Experiment 1 Second Experiment 1 Failed Experiment 1