Coordinate 72 (72-hour mapping challenge)
Coordinate 72 was created for the 72-second mapping challenge:
https://www.runthinkshootlive.com/posts/the-72-second-experiment/
The aim of the challenge was to make a map that would only be playable for 72 seconds, within the span of 72 hours. Contestants were encouraged to make maps with replayability in mind, and the players wouldn't necessarily be expected to complete the map within the first 72 seconds they play for.
Coordinate 72 forces the player to make a choice between attempting to escape an exploding facility themselves, or override an exit portal's security systems to save their companion, Alyx. They are only able to complete one of the two goals within 72 seconds, with the Escape sequence being combat-oriented, and the Save sequence being focused on puzzles and slight platforming. The map can be replayed so the player gets both endings, or neither if they do not escape or save Alyx in time.
Created in Source Engine using the Hammer Editor.
Walkthrough Video
At the beginning of the map, the player can see that Alyx has been trapped by herself in a non-functioning portal. When approached, she says that the player must reactivate it. The player then has two clear paths to choose from.
If the player chooses to go towards the door where soldiers appear to be escaping from the exploding facility, it will soon close and force Gordon down a detour.
An opening in the side reveals a large Combine structure and the player can see a floating elevator platform approach.
After stepping onto the elevator, the player loses their regular arsenal and instead gains a supercharged gravity gun to be used against on higher platforms.
Hunters are present on the platforms alongside soldiers, and they can only be killed using energy balls picked up by the gravity gun.
After the player reaches the top exit of the elevator, they can escape the facility, leaving Alyx to die.
If the player instead chooses to go to the control room to reactivate the portal, a non-action route needs to be traversed.
The only way forward is through the Combine energy ball tunnel.
As the player leaves the tunnel, they step into a room with electrified water and have to make their way around on the pipe, with barnacles occasionally blocking the way. All of this has to be done under the 72 second time limit.
The electricity is deactivated at the end of the room where the power switch is located.
When the player jumps through the vent to the control room they become trapped and cannot go back, which is necessary for the chosen ending.
After the console is activated, Alyx rises up to the teleport platform and thanks Gordon for what he's done for her.
As she teleports away, the player can witness the facility exploding behind them.
Ending text when you save Alyx.
Ending text if the player is not fast enough to achieve either of the two main endings.