The Portal Device is the first area in the prototype. It starts in a small room with a machine in it, right after the disaster happens. Instead of going through ruined dormitories and labs, the player has to go through cages containing captured specimens in order to disable a door that has been locked down with an emergency lock.
This area was retooled and greatly expanded into Unforeseen Consequences.
C1a1
One of the airlocks in this map was flipped and reused for the airlock the player enters after getting the Pistol from a dead Barney, while a ruined computer room was repurposed for the large computer room the player has to go through from the lobby in Unforeseen Consequences.
Prototype
Final
Prototype
Final
Prototype
Final
C1a1a
This map has the player go through several caged areas containing aliens and the occasional scientist in order to deactivate an emergency lock.
This map appears in a few pre-release screenshots.
Prototype
Prerelease image
C1a1b
This map contains two offices and a storage area filled with aliens. One of the offices was reused for the electrified water room just past the start of Office Complex.
Prototype
Final
The Office Warrens
The Office Warrens is the second chapter in the prototype.
It follows the same flow and style of the final's Office Complex. However, the prototype introduces the Human Grunts in this chapter, while the final game moves their first appearance to the next chapter, presumably to give the player more time to fight the aliens and get acquainted with the game more before fighting Human Grunts.
C1a2a
This map is actually a prototype version of the final's c1a2 and c1a2a, merged into one map.
Many sections that appear in both the prototype and the final game are shorter and simpler; the lighting and textures are far less detailed than they are in the final game. The floor plan was opened up in several areas to be more variable and interesting.
General Differences
No baseboards were on the brick walls yet.
All wooden trim is darker brown in the prototype.
Doors are either wooden or light green rather than red or gray in the final.
Metal door frames are light green instead of red.
Ventilation shafts are not fully functional yet.
Many of the ceiling lights were shut off in the final.
Room Differences
Prototype
Final
No vent in this corridor.
Table with headcrabs is not present.
Prototype
Final
Prototype
Final
There used to be a wooden coffee table in front of the couch.
Prototype
Final
Prototype
Final
Prototype
Final
This room is not flooded in the prototype.
The hole in the ceiling was punched through a tile, with cartoonishly thick chunks of plaster on the floor. The final had one of the lights pushed out by the Barnacle hole instead.
The corner with a bookcase and filing cabinet was filled in with a wall and a ventilation grate was added instead.
The desk was redesigned and several tables and a cabinet were added to the room.
Prototype
Final
The door was moved to the long side of the hallway instead of the short end.
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
The ladder doesn't extend all the way to the floor.
C1a2̠b
This map combines prototypes of the final's C1a2b and C1a2c into one map. However, the elevator shaft with ladders room has been moved to a separate map.
The freezer section is much simpler in this prototype. A good chunk of the area is missing and the player has to use crates to reach the vent grate near the back instead of using a lift system to reach the vent system. The vent room and maze after the freezer area is an optional part of the map in the prototype.
The demo for this map reveals that the player would have to avoid a Human Assault in the kitchen cafeteria area. The final game replaces him with Headcrabs and Zombies.
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
C1a2c
This map is completely different than the final's C1a2c. It's mostly a set of hallways that lead to the elevator shaft with ladders that appears in the final's C1a2b.
What's interesting is that this map has breakable holes that match how some Zombies break through walls in the final game, but there aren't any Zombies in the prototype. This suggests there were Zombies in the game at this point in development, but were removed for the press demo for some reason.
Prototype
Final
Prototype
Final
Prototype
Final
The Security Complex
The Security Complex is the third chapter in the prototype. In it, the player has to activate a switch near the surface in order to open the door to a silo.
We've Got Hostiles uses the same map names and general motifs that The Security Complex has, suggesting that The Security Complex became We've Got Hostiles.
C1a3
C1a3 starts just like the final's C1a3 does; in an elevator. The player's objective in the chapter, a door to a silo, is to the right one the player gets out of the elevator, but the door cannot be opened because of scripting issues.
Most of the map takes place in a warehouse filled with Houndeyes and Human Grunts.
This map appeared in some pre-release screenshots.
Prototype
Prerelease image
C1a3a
C1a3a takes place in a maintenance area. An elevator to the surface is in the map, but there is a turret in the way that the player is supposed to deactivate.
The most prominent part of the map is a puzzle involving a ventilation system. The player has to use switches so that doors in the vent system lead to the switch to deactivate the turret. If the player opens or closes the wrong doors, he will be sliced up by fans. A picture to the right of the switches shows how they should be opened.
This map appeared in some pre-release images.
Prototype
Prerelease image
C1a3b
C1a3b is a map that is used to transition from one part of C1a3a to another. It is set in a partially-flooded warehouse area that's filled with Bullsquids and Headcrabs. A vital walkway can be destroyed by gunfire or stray Headcrabs.
This map appeared in some pre-release screenshots. It's interesting to note that these screenshots show an updated HUD and the headcrab model from the final game, suggesting that the level was kept for a while longer before being scrapped.
Prototype
Prerelease image
C1a3c
This map is in a small bunker at the surface. The player has to defeat some Human Grunts, then hit a switch at the bottom of the bunker to activate the door to the silo in C1a3. However, the switch does not work.
Near the switch is a vent the player can access. It leads into a completely-unrelated area in C1a2a.
The player can exit the bunker and run around the outside area with a crouch jump.
It appears in some pre-release images.
Prototype
Prerelease image
Alien Research Lab
This is the next chapter available in the prototype. Based on its name and general theme, a lab researching the aliens, it is a prototype version of Questionable Ethics.
C2a4
This map is in a tiny warehouse area filled with some Human Grunts.
C2a4a
C2a4 is in an underground area and contains the main objective in the map; a room containing two retinal scanners and a door. The player is meant to bring two scientists from the next map, C2a4b, to the retinal scanner room to open the door. But, the scanners do not work and there is not a trigger to C2a4c behind the doors, forcing the player to use the "map" console command to reach it. This is similar to how the player exits the lab in Questionable Ethics.
This map has a Human Assault in the large area the player enters at the start, but he can only be seen in the demos. Based on the demos, the player was meant to crouch behind some gaps in the buildings near him to slip by him.
This map appeared in some pre-release images.
Prototype
Prerelease image
C2a4b
This is a large and twisting lab area filled with corridors that the player has to navigate in order to find two scientists. However, the map is filled with Human Grunts patrolling the area. There is also a room filled with Alien Grunts in tanks in it, though there is no way to do anything with them.
This map appeared in some pre-release screenshots.
Prototype
Prerelease image
C2a4c
This is the final map in Alien Research Lab. After opening the retinal scanner-locked door, the player has to activate the emergency button in order to release the locks to the surface.
A few screenshots of this map appeared in pre-release materials.
Prototype
Prerelease image
Communications Center
Communications Center is a mish-mash of the final's Forget About Freeman! chapter (mostly in the starting area) and the multiplayer map Datacore. The intended goal of this map is to activate a communications satellite in order to shut down an emergency lock that prevents the player from going to the next area. However, the lead scientist in the area that tells the player about the satellite is a traitor and was meant to sic some Human Grunts on the player after he dealt with the satellite. There is no scripting for this area, so all the player can do is walk around, shoot some enemies, and check out the layout.
All of this location is in one map: c3a1.
The concept for this area was reused for the Half-Life: Uplink demo.
Prototype
Final Forget About Freeman!
Prototype
Final Forget About Freeman!
Prototype
Final Forget About Freeman!
Prototype
Final Forget About Freeman!
Prototype
Final Datacore
Prototype
Final Datacore
Hidden Barney
This map also contains a "hidden" Barney, inside of a blocked-off room. Pre-release screenshots of this area show that there was a door leading to this area at one point.
(Source: Theuaredead)
Xlabs
Xlabs is a prototype version of Lambda Bunker. It follows the same flow the first parts of that chapter has.
C3a2
This map takes place in an underground area filled with aliens and turrets. The player has to fight his way to the Xlabs, just like how the player fights to the Lambda Bunker via an underground area in the final game.
Prototype
Final
C3a2a
This is an early version of the lower core part of Lambda Bunker. The player is intended to flood a core with coolant, like in the final game, but the scripting for this does not exist, so all the player can do is explore and fight aliens.
Based on the map's layout, it would flow the same as the final's take on this version the player would have to go to areas filled with pools in order to activate the coolant. However, the map design is much less complex than it is in the final game.
Prototype
Final
Prototype
Final
Prototype
Final
Prototype
Final
Maindemo
Maindemo is a map that was used in the E3 1997 demonstration. The map contains a lobby, a showroom featuring almost all of the enemy models, a computer-filled room with NPCs and a Headcrab, and a room that has a walkway over Bullsquid-infested water.
Prototype
Prerelease image
Prototype
Prerelease image
Silodemo
Silodemo is a map that was used in the E3 1997 demonstration that shows off the Tentacle enemy in a simplified version of its final room and a warehouse area filled with Human Grunts that demonstrates the Human Grunt's AI. The Human Grunt area uses box textures that appear nowhere else in the prototype, suggesting these are old box textures that were not updated to use the textures that are used in both the prototype and final games.
Prototype
Prerelease image
Prototype
Prerelease video
Techdemo
Techdemo contains rooms that show off colored lighting (even when using the software renderer), the bone animation system with a test NPC, transparency, flocking behavior with the Boid enemy, the DSP sound system that shows off effects like reverb in certain rooms, a scripted sequence featuring a Security Guard throw a scientist to the ground, then the scientist gets eaten by a Panthereye, and a room with a high-poly model to show off how many polygons on a single model the engine could handle.
Prototype
Prerelease image
Warez_dm
The prototype contains a single deathmatch map called warez_dm that eventually became the final's Stalkyard.
Surprisingly, most of warez_dm's architecture is the same as Stalkyard's. Warez_dm lacks the machine gun emplacements, the goodie-filled room on the upper floor of the map, and items.
This map uses vents one can crawl up as an alternate way to get to the upper floors. The final game replaces them with conventional ladders. Several health cabinets in warez_dm were either removed or replaced, but some of them were repurposed into Health Chargers or HEV Chargers.
