STRAIN

STRAIN is a 32-level partial conversion for Doom II released in 1997 by the Alpha Dog Alliance. It features nine new or modified monsters through the use of DeHackEd, modified weapons, and a soundtrack written by David "Tolwyn" Shaw, Mark Klem, and Jon Landis. The project had a sporadic development history, exceeding a year due to cyclical interest and disinterest.

Story
STRAIN occurs after the events of Doom II. A military officer in a secret base on the Earth's moon has been engineering demons, creating a new breed of Hellspawn which breaks free of its confines, making an initial landing on Earth. The Doom marine undergoes an experimental treatment to increase his combat potential. Its side effect is that it leaves virtually all of its subjects in a state of perpetual, murderous aggression. The in-game story follows four episodes as the marine fights to an infested spaceship that's landed on Earth, afterward battling his way deep into the heart of the secret installation where the demons originated from.

Levels
First "episode": Second "episode": Third "episode": Final "episode": Secret levels:
 * MAP01: Barracks by Bill McClendon
 * MAP02: Outskirts by Bjorn Hermans
 * MAP03: Downtown by Florian Helmberger
 * MAP04: Industrial Zone by Adam Windsor
 * MAP05: Depot by Jon Landis
 * MAP06: Launch Control by Jon Landis
 * MAP07: En Route by Adelusion
 * MAP08: Hangar by Rich Johnston
 * MAP09: Cargo Bay by Adelusion
 * MAP10: Entryway by Charlie Patterson
 * MAP11: Command Control by Bill McClendon
 * MAP12: Power Station by Bill McClendon
 * MAP13: Ruins by David Rotramel
 * MAP14: Engineering by David Graves, Adelusion, Rich Johnston, and Arthur Chang
 * MAP15: Subsidiary Power by Chainsaw
 * MAP16: Living Quarters by Charlie Patterson and Eric Roberts
 * MAP17: Promenade by Holger Nathrath and Arthur Chang
 * MAP18: Relay Station by David Rotramel
 * MAP19: Waste Processing by Darrell Esau
 * MAP20: Reactor by David Davidson
 * MAP21: Maintenance by Adelusion and Arthur Chang
 * MAP22: Specimen Storage by Adelusion
 * MAP23: Dispensary Alpha by Adelusion
 * MAP24: Sub-Laboratory by Adelusion
 * MAP25: Main Laboratory by Arthur Chang
 * MAP26: Main Laboratory II by Holger Nathrath, Charlie Patterson, and Eric Roberts
 * MAP27: Dispensary Beta by Andy Badorek
 * MAP28: Unknown by Bjorn Hermans
 * MAP29: Self-Destruct by Ron Allen
 * MAP30: Boss by Jon Landis and Rich Johnston
 * MAP31: Secret by Jon Landis
 * MAP32: Super-Secret by Holger Nathrath and Adelusion

Weapons
STRAIN modifies the original Doom weapons as follows. STRAIN makes several other core gameplay changes.
 * Fist: The marine punches quickly with both fists in succession. Both swings are boosted by the berserk powerup.
 * Pistol: Fires faster.
 * Shotgun: New graphics and fires faster.
 * NFG: Replaces the plasma rifle. Its base damage is 7 points higher.
 * Psychic Blaster: Replaces the BFG9000. It consumes three rockets per shot, launching partially invisible projectiles at a faster rate that only cause blast damage.


 * Players begin with no ammo at pistol start
 * Cells are capped at 50 (100 with the backpack)
 * Megaarmor sprite is replaced and increases armor to 300 percent.

New monsters
Usage of new tiles and DeHacked editing creates several new monsters for the game:


 * Imps which move much faster and throw fireballs in a rapid manner now replace the Arachnotrons. They have no visual distinction from normal Imps (which are in the WAD) but have a higher-pitched alert noise. They will literally run in a player's face faster than can be seen and are hard to target due to their speed. They take slightly more damage as well.
 * Demons are now red and take slightly more damage (a super shotgun blast will kill in one shot, assuming all 20 pellets connect).
 * Flying drones replace the Revenant gaining a Cacodemon-like hover ability. They fire both types of Revenant missile, both of which travel at roughly half the normal speed and are much easier to dodge. They can also be found stealthed much like the Spectre.
 * Lost Souls now have blue and red flames with longer horns, and in addition to the standard ramming attack, now fire Imp fireballs.
 * Cyberdemons are now half normal size with higher-pitched alert and walking sounds. They take roughly 4-6 rockets to kill, but still fire normal rockets themselves, offsetting the comical idea of a miniature cyberdemon.
 * Presumably replacing the Spider Mastermind are flying cubes (taking grapics form the Icon of Sin's enemy spawn cubes). Their alert sound is a human voice saying "Got Him!". They fire the Spider Mastermind's chain shotgun.
 * The Mancubus is replaced by a superchaged Baron of Hell, with gray skin and green legs. They toss five green plasma balls at once in a spread pattern.
 * Certain zombie troopers fire off BFG-9000 rounds in later levels. There is no visual distinction between normal and BFG troopers until they fire.
 * Chaingunners have a new graphic set wearing the Marine helmet. The player sprite uses the same sprite set.
 * Cacodemons, Hell Knights and Barons of Hell toss their projectiles much faster.

Other notes
MAP07: En Route is impossible to complete in ports based on old versions (prior to 2.3.0) ZDoom, as the level relies on the occurrence of a spechits overflow in order for the exit to work. Recent versions of ZDoom identify the map and automatically apply the required compatibility flag. There also problems with the DeHackEd patch when it is used with Doom Legacy. Doom Wad Station provides a fixed version at their STRAIN Page.

A few of these levels first appeared in Dystopia 3. MAP23 is an example. Additionally, MAP17, MAP18, and MAP24 share a room giving a sense of partial continuity.