National Treasure 2 Balance Trap: How?

[Chaldfont]

I watched National Treasure 2 the other night and immediately thought the balance trap would be great for a 4th Edition D&D encounter.

But how do I represent it mechanically? Basically, my goal is to have the players try to balance the floor while they fight their foes. I want to be able to quickly, at the end of a round, determine which way the floor is tilting and have everyone slide a number of squares in that direction (maybe avoiding the slide with an Athletics or Acrobatics check). I want the distance of the slide to increase as the tilt increases and I want to know if the floor has tilted so far that it dumps every one off.

I started to apply high school physics to the problem but I realized that would take way to long at the table. I'm looking for a simple mechanism like:

Count the number of characters in the North half minus the South half and slide everyone that many squares to the North (or South if it's negative) and do the same thing for the E/W direction.

Of course, you have to be careful you don't slide everyone off on the first turn!

How would you do it?

 

[Chaldfont]

Ok, I thought of another way that greatly reduces the time to figure out which way the thing is tilting.

1) Make your square out of cardboard and cut a small hole in the center.
2) Place it on a d4.
3) Put all the minis on your new dungeon tile.
4) Bask in the adulation from your players.
5) Slide each character 1 or 2 squares in the direction of the tilt.

 

[Scribble]

I think the easiest thing woud be to compair who's on what side...

Have size categories = 1/2 of trhe next larger size? Like 2 small = 1 medium, 2 medium = one large.

1st round the trap attacks all characters on board. If it hits, they slide a certain number of squares. (how dangerous you want it to be.)

people get to make a save to see if they can make a skill check to move, or if they just spend the round "trying to stop from sliding."

The idea being to get enough people spread out around the trap to "nullify" it?

 

[Random Axe]

I think you may have to also somehow account for degrees of encumbrance? Not just size categories, but whether the PCs are wearing heavy armor or not, carrying large amounts of equipment or not, or whether they dump their equipment to even the balance (thus ridding them of something valuable or necessary for a later scene that they will have to cope with?)

One factor that remains true is that the further out towards the edge of the platform one stands, the more tilt it creates (and the more slide caused, the higher the difficulty to stay balanced, etc). The character would need to move toward the center of the platform to ease the tilt.

If you have NPCs on the platform with PCs, then you could call for leadership rolls from the PCs as they call out instructions or directions to the NPCs.

 

[Filcher]

Ok, I thought of another way that greatly reduces the time to figure out which way the thing is tilting.

1) Make your square out of cardboard and cut a small hole in the center.
2) Place it on a d4.
3) Put all the minis on your new dungeon tile.
4) Bask in the adulation from your players.
5) Slide each character 1 or 2 squares in the direction of the tilt.

If this works, definitely this way.

 

[IanB]

If you could find one, a 5 sided pyramid (like the pyramids at Giza) would probably work a little better than a d4.

 

[jmucchiello]

If you could find one, a 5 sided pyramid (like the pyramids at Giza) would probably work a little better than a d4.

Excellent, I'll gather 100,000 of my peasants/slaves and build a pyramid like the one in Giza for my next D&D session.

On topic: The problem is the tilting platform relies on live physics while the D&D combat system is tile-based and turn-based. You have to coordinate movement to the second and moving in 5-foot increments is not recommended. The first time someone takes a step out of turn, the whole thing would probably collapse as 4 other people (in their attempt to compensate for the unexpected movement) overcompensate and tip the whole thing over. Otherwise you have a lot of readied actions that happen at once.

 

[Celebrim]

It isn't going to be easy to do with squares. Squares aren't refined enough of a measurement.

You probably will end up needing to count both squares and feet.

So, imagine this is your balance, eleven squares numbered. Let's say the platform is 15' wide.

-5 -4 -3 -2 -1 0 1 2 3 4 5

At the beginning of each round, for each occupied square, add its number to your running sum.

Suppose you have 2 characters in the -4 row, two in the -3, two in the 2 row, and one in the 5 row. That's -4 + -4 + -3 + -3 + 2 + 2 + 5 = -7. Slide everyone 7' to the left. This is approximately 1 square, so represent this as 1 square, but keep track of that extra 2', and carry it to the next round. So if for example, next round everyone slides -8 feet, that's extra -2 carries and everyone slides 2 squares.

Likewise, carry the slope results of each previous round to the next.

At the beginning of first round of instability, the four characters were at -5, -5, -4, -4, -1, -1, and 4. After their actions, they are now at -3, -2, -1, 1, 1, and 4 and there is a dead body in -5. This is a total of -5, which together with the total from the previous round brings the slope to -12. Slide everyone two squares, and carry the remainder (-2 plus the -1 from the previous round, or -3) into the next round. The dead body slides off the end, and now the characters are in -5, -4, -3, -1, -1, and 2.

Now, some special rules.

If the absolute value of the slope goes above 10, consider movement to be difficult terrain.

If the absolute value of the slope goes above 15, not only is movement difficult terrain, but you must make an atheletics check vs DC 15 to move up the slope at all.

If the absolute value of the slope goes above 25, everyone must make an atheletics check vs. DC 30 to move up the slope at all.

PS: Don't describe the rules to the players. Just describe the outcomes.

 

[Festivus]

Slightly off topic, but wasn't that same trap in the latest Indiana Jones movie?

In 4E, for the trap, have the floor make an attack vs reflex. If it beats their reflex defense they are knocked prone, beat it by 5 they also are pushed 1 square from the center, 10 = 2 squares.

The attack modifier can be adjusted for things like if the stone is greased, sandy, wet, etc. It shouldn't matter which side of the trap they are on, however if they figure out how to balance it with four characters on each quadrant, subtract from the attack roll by -1 for each balanced corner (e.g. if two and two are on opposing sides, -2 to the attack).

 

[Umbran]

Okay, I could come up with something like a quick way to figure out where the center of mass of the party is, and translate that into some amount of tilt.

However, it is entirley possible that with any particular set of part and monsters, it would be very easy to end up with an arrangement from which the party cannot reasonably extricate themselves. If you phrase the operation in terms of math, you may find a situation where there is no "right" thing the PCs can choose to do to survive. Doubly so if some of the antagonists are not really worried about survival.

In the movie, the point is that the protagonist and antagonist had to cooperate to survive, rather than engage in a fight. And they had a small number of people to deal with, they quickly simplified the problem, and they had a certain amount of script-immunity

I wouldn't phrase this in terms of anything trying to be "real" physics. It would take too long to do calculations, and it wouldn't add to the tension of the scene. I'm thinking about phrasing it in other terms, possibly system-agnostic ones.