Fake Elevators
By Jason Harper, JasonHarper@pobox.com
From the "Missed Island" map

Coming up next is another trick for doing elevators that stop at more than two floors. See the diagram (made with the help of a demo version of Gryphon Bricks™) for details:

Red - first floor.
Green - second floor.
Blue - third floor.
Gray - elevator shaft.
Brown - entrance, to the right of this terminal. It goes past the 2nd floor, then stairs lead down to the 1st floor.
Yellow - storage area, on second floor.
Purple - exit, on third floor.

And yes, all three floors connect to the same side of the elevator... Your goal is to reach the exit on the 3rd floor, but you will need to pick up an item on the way. (Editors Note: In the map you will now be expected to operate the elevator - gls)

Did you figure out what the trick was that allowed multiple elevator exits through the same door?

Hint: the diagram of the area [above] has almost NO connection to the actual layout of the floors.

Again, this effect is a total fake. The "elevator" doesn't actually move at all: it IS a platform, but only so that it appears as red on your automap. The area just outside the elevator door consists largely of platforms that do move, reconfiguring the area into the appearance of three separate floors. These platforms are flagged as Secret so that they don't appear as platforms on your map, except for the thick line around them (there will be more details on working around that problem later).

The version of the 2nd floor that you can see from the entry corridor is a fake duplicate. Likewise, the version of the corridor that you can see from the "real" 2nd floor is also a fake. The entry corridor loops over the 1st floor purely for the sake of misdirection: it obscures some of the boundaries between platforms, that would otherwise result in thick lines appearing on the map for no obvious reason (usually a dead giveaway of a secret platform).

Some other platform edges were obscured with the following trick: if any of the textures on a line (high or low, on either side) are landscapes, then the line will appear thin on the automap regardless of any other considerations. There are three instances in this demo where a far side of a platform is given the landscape texture. You can never actually see these sides, since you can't get to that side of the platform unless it is lowered (if you can even get there at all), but they still affect how the line appears on the map. The results aren't perfect: ideally there would be no line at all in these instances, rather than a thin line. But at least they avoid an unexplained thick line, which any experienced Marathon player would recognize as a sign of a secret platform.

(The same trick was used on Missed Island to conceal the fact that the big sunken ship and large upright gear are actually composed of platforms which can move. In these cases, the ceiling height was made different over each platform, and the resulting high walls were landscape textured.)

The control mechanism for the elevator is fairly complicated, since the set of platforms which have to be raised or lowered depends not only on the floor you're moving to, but also the floor you're currently on.

A modification of the Enforcer/Tick shooting gallery idea is used, as shown in the diagram here. One Enforcer is enabled, based on the current floor, and one Tick is enabled, based on the floor button which has been pressed. Each of the nine possible lines of fire strikes a switch. For the six possible transitions between different floors, the switch is a tag switch which activates the appropriate platforms. For the three possibilities of pressing the switch for the current floor, the lines of fire all hit the center switch, which is simply a platform switch that reopens the elevator door.

All of the switches are light-activated, and one of the first effects of activating any of the switches is to darken that light. This prevents multiple switch activations per use of the elevator, which would leave the puzzle in an unpredictable state.

The same light also controls a liquid level, which floods the Ticks with lava in order to kill them (they immediately reappear, due to the monster parameter settings). This is necessary to get the Enforcers to accept the next Tick revealed as their new target: otherwise, they would remain locked onto the original Tick even though they no longer had a line of sight to it. (My wife keeps threatening to report me to the Society for the Prevention of Cruelty to Ticks. Do you think she might have a point?)

If you'd like to see this control room in operation, there is a way to access it. Return to the elevator, and punch out the three light fixtures along the back wall. You'll then be able to walk through this wall, into a teleporter that will take you to the control room. (The control room has a teleporter that will return you to the elevator.) It would be a good idea to save the game first, since it's possible to screw up the elevator mechanism by killing the Enforcers, or hitting the control switches yourself in an inappropriate order.

As with the demo AND gate you saw earlier, there will be some texture smearing in the control room where liquid levels are being used in unsupported ways. This wouldn't be a problem in an actual level using this technique, since the player would never be allowed into the control room.

As with the bridge trick, this elevator design is only suitable for use on a solo level. It would NOT be a pleasant experience to be a player out on one of the floors, at the time that another player activates the elevator...

Also, combat with corpse-leaving creatures must not be allowed, at least not in the shared areas of the floors, to avoid having the corpses inexplicably visible in the same place on other floors. Other combats can take place in areas reachable from only one of the floors: for example, there could have been a guardian of some sort in the 2nd floor storage area where you found the uplink chip. Just make sure that any such creatures are blocked from the shared areas via a Monster Impassible polygon.

FAKE ELEVATOR - SUMMARY
The resources used by this 3-level elevator are:

• About 39 platforms (ouch!)
• 12 lights
• 6 tags
• 4 liquids
• 3 Enforcers + 3 Ticks
• 6 sound objects

Note: the complexity of the control mechanism grows rapidly with the number of floors. A 4-level version might barely be possible, but any more floors would require a simpler control mechanism design. One possibility would be to have buttons to move up one floor, down one floor, and open the door, rather than having buttons for direct access to each floor. This would require 2N-2 different floor transitions to be implemented instead of N^2-N.

IDEAS FOR FURTHER DEVELOPMENT

• Much better use of lighting could be made to give each floor a distinct appearance. Currently, only one light varies between floors (the darkened frame of the window on the 2nd floor).
• The illusion of vertical movement could be strengthened by having the lowest floor partially flooded. This would require a light that is activated only when on that floor, that controls a liquid applied throughout the floors. I would have done this for the demo, except for the fact that I was long since committed to the lava texture set before the idea occurred to me...
• The previous idea could be extended by having the lowest floor completely underwater, with the next floor up being partially flooded. Implementing a liquid with three distinct heights is left as an exercise for the reader. Hint: I'm pretty sure that this is possible, using a light with extremely long transitions. However, the liquid height would slowly drift from at least one of the levels, so some compelling reason (such as an oxygen recharger on another floor) must be provided for the player to periodically use the elevator, so that the liquid level gets reset.

Missed Island