Some statistics on old games vs new (Zork vs CM)

I was talking about different kinds of big adventures before, trying to figure out what made games like Zork take so long to finish.

I did a rough analysis of all of the puzzles in Zork, estimating how far you have to travel for each puzzle, what kind of solution they require, and which puzzles depend on each other. I also did a rough analysis of Counterfeit Monkey.

This is a long, rambling post.

Zork I puzzles analysis (summarized below)


Most of the puzzles involve getting one or more of the treasures.

Jeweled Egg

-Objects Required: noun

-Obstacles: Unlisted room exit

-Hints: Big tree with low branches mentioned in room description

-Red herrings: Room has similar description to numerous other forest rooms

-Distance between all objects and hints: 0

Clockwork Canary

-Objects Required: Jeweled Egg

-Obstacles: Must be opened by thief. Requires leap of intuition or exhaustive experimentation.

-Hints: Thief may automatically steal egg. Egg is described as extremely fragile. Opening says "You have neither the tools nor the expertise."Thief described as nimble.

-Red herrings: Many possible ways to open egg: dropping it, hitting it, breaking it, submerging it, sitting on it, etc. No reason to suspect egg should be opened; desire to keep thief from taking objects.

-Distance between all objects and hints: 6 (between nest and underground) or 3 (if grating is unlocked)

Brass Bauble

-Objects Required: Clockwork canary

-Obstacles: Must know where to wind it (in Up A Tree). Requires leap of intuition or exhaustive experimentation.

-Hints: Winding it says that the canary chirps. In the room where you need to wind it, you hear a distant chirping.

-Red herrings: Wind-up canary might have been useful in many rooms (including echo chamber), or not at all.

-Distance between all objects and hints: 8 from thief’s lair to nest.

Beautiful painting

-Objects Required: None

-Obstacles: Must reach basement. Must find a way out of basement.

-Hints: none.

-Red herrings: none, really. Just need a way out of the basement.

-Distance between all objects and hints: 0

Platinum bar

-Objects Required: Wrench (for one method) or none (for other)

-Obstacles: Commands are repeated, making taking impossible. You must make a leap of intuition using outside knowledge to say ‘echo’, or use the hint to open the dam, close it, and come back, probably requiring exhaustive experimentation.

-Hints: The room above it says that a sound from below sounds like ‘rushing water’.

-Red herrings: There are other sound-producing objects in the game that may have a use here. Could be a wordplay puzzle.

-Distance between all objects and hints: 0 (for intuition) or 4 (if wrench is used)

Ivory torch

-Objects Required: Rope

-Obstacles: Must figure out that you need to go down from dome room, go down, and then get back out.

-Hints: There is a clear hint that you can go down from the dome room, and you’ve had a rope since almost the beginning.

-Red herrings: Several other areas with pits that the rope might work in, jumping down, etc.

-Distance between all objects and hints: 10

Gold Coffin

-Objects Required: None (beyond what’s needed for torch puzzle)

-Obstacles: Getting to the temple area, getting it out of the temple area requiring a leap of intuition.

-Hints: When you try carrying the coffin out of the only exit, it says 'You haven’t a prayer of getting the coffin down there." Also, there is an altar nearby.

-Red herrings: Tying the rope and throwing it up might work, lightening it by emptying it, pushing it in the hole, etc.

-Distance between all objects and hints: 2 (between coffin and altar)

Egyptian Sceptre

-Objects Required: Gold Coffin

-Obstacles: Knowing you can open the coffin, possibly requiring outside knowledge (that sarcophagi were openable)

-Hints: None that I saw

-Red herrings: None really

-Distance between all objects and hints: 0

Trunk of Jewels

-Objects Required:Wrench

-Obstacles: Figuring out how to work the dam (with the buttons and wrench), knowing what effect that would have on the world (both solved with experimentation)

-Hints: None, really; the bolt and buttons are asking to be solved, and you would naturally explore after figuring them out.

-Red herrings: None; there’s no reason to expect anything to be here at all, or the reservoir to be drainable.

-Distance between all objects and hints: 3

Crystal Trident

-Objects Required: None (beyond what’s needed for reservoir puzzle)

-Obstacles: None. This is a gimme.

-Hints: None needed.

-Red herrings: None needed.

-Distance between all objects and hints: 0

Jade Figurine

-Objects Required: Garlic

-Obstacles: Getting past reservoir, solving the bat (requiring outside knowledge)

-Hints: The bat is a vampire bat, and vampires hat garlic.

-Red herrings: Garlic is edible, many monsters might want to eat it. Bat seems like a transportation system that needs to be solved.

-Distance between all objects and hints: 15!

Sapphire Bracelet

-Objects Required: An anti-object is required: you have to drop the ivory torch

-Obstacles: Figuring out how not to blow up the room; the coolness of the ivory torch vs. the brass lantern.

-Hints: The room before the instant death is underground, in a mine, and described as having a foul odor.

-Red herrings: Room might just be a dead-end, ivory torch is better in all other ways than lantern.

-Distance between all objects and hints: 0 (if you already have the lantern)

Huge Diamond

-Objects Required: coal, screwdriver

-Obstacles: Finding the coal, getting to the machine with the basket, figuring out how to use the machine, all requiring exhaustive experimentation

-Hints:The machine is burning things up (I think?) and coal can be turned into diamonds (more outside knowledge)

-Red herrings: coal can be burned, anything could be put into the machine, screwdriver has many other uses and may no longer be carried

-Distance between all objects and hints: 25! (between screwdriver and machine)

Bag of coins

-Objects Required: None

-Obstacles: Getting through maze

-Hints: none

-Red herrings: This room is the first to be reachable by the ‘up’ direction.

-Distance between all objects and hints: 0

Crystal Skull

-Objects Required: Bell, Book, Candles

-Obstacles: Getting to the temple area, guessing the ritual requiring extreme experimentation or outside knowledge

-Hints: The temple is near the cave, outside knowledge suggests these objects can be used against spirits.

-Red herrings: Candles are a light source, bell might be useful as a sound source in other areas, book could be treasure or flammable object

-Distance between all objects and hints: 4 (between bell and crystal skull)

Jeweled Scarab

-Objects Required: Shovel

-Obstacles: Getting to the sandy beach area, knowing you should persever in digging

-Hints: the sand is right next to the shovel, and sand is one of the most shovelable things in the game

-Red herrings: Nowhere else in the game are repeated actions required, especially without encouraging feedback. Many shovelable things exist (coal, for instance)

-Distance between all objects and hints: 2

Large Emerald

-Objects Required: None (besides getting in the river)

-Obstacles: Knowing the buoy is openable/takable

-Hints: None that I know of. Maybe examining it? Touching it seems to say it feels weird.

-Red herrings: No indication buoy is nearby, or any real hint that opening it is useful. Maybe you would consider dropping it somewhere else in the river or throwing it off the waterfall?

-Distance between all objects and hints: 1 (getting it out of the water)

Silver Chalice

-Objects Required: Wicked Knife (essentially)

-Obstacles: Getting through the maze, killing the thief, getting out through Cyclops

-Hints: The thief is clearly painted out as an enemy. Cyclops is described as hungry (food works, then water because food is spicy). Odysseus solution requires outside knowledge.

-Red herrings: Thief can be battled in many areas; diagonal directions required; many possibilities for killing the Cyclops.

-Distance between all objects and hints: 11 (between knife and thief)

Pot of Gold

-Objects Required: Sceptre (and getting to falls)

-Obstacles: Giant leap of intuition knowing you need to wave the sceptre.

-Hints: Having played Adventure?

-Red herrings: Throwing rope across chasm, jumping, using sceptre for other things

-Distance between all objects and hints: at least 15 (hard to count)

Ancient Map

-Objects Required: All

-Obstacles: All of them

-Hints: N/A

-Red herrings: N/A

-Distance between all objects and hints: Too big

Puzzles opening up areas

Entering the House

-Objects Required: none

-Obstacles: Finding which side has an entrance

-Hints: N/A

-Red herrings: Front door

-Distance between all objects and hints: 0

-Puzzles unlocked: all except tree

Entering basement

-Objects Required: none

-Obstacles: Leap of intuition to look under rug

-Hints: none (maybe taking the large rug because it’s expensive?)

-Red herrings: large outdoor area

-Distance between all objects and hints: 0

-Puzzles unlocked: all treasures except egg

Killing troll

-Objects Required: sword/knife

-Obstacles: troll itself

-Hints: Sword glows blue, troll attacks you

-Red herrings: none

-Distance between all objects and hints: 2

-Puzzles unlocked: all except tree, painting


-Objects Required: none

-Obstacles: hidden exits

-Hints: none; stereotypical maze

-Red herrings: first part only requires standard n/e/s/w

-Distance between all objects and hints: length of maze

-Puzzles unlocked: skeleton keys, coins, chalice/thief, cyclops

Entering torch room

-See torch puzzle

-Puzzles unlocked: Egyptian coffin, hades, aragain falls/sceptre, basket puzzle/machine/diamond

Reservoir lowering

-see trunk of jewels

-puzzles unlocked: trunk of jewels, crystal trident, bat/jade figurine, gas room/sapphire bracelet, basket/machine/diamond, pump and boat area, one method of solving loud room/platinum bar


-Objects Required: pile of plastic, pump

-Obstacles: knowing that the plastic can be inflated (mild out of game knowledge required), not popping it (experimentation), possibly requiring repair glue from dam

-Hints: A valve suggests inflation, popping implies sharp things

-Red herrings: inflating with breath

-Distance between all objects and hints: 4

-Puzzles unlocked: buoy/emerald, shovel/scarab, falls/pot of gold

Other puzzles

Knowing to put things in the trophy case: requires leap of intuition (checking score and trying to put stuff in the case)


How many treasures can you have unsolved simultaneously (i.e. with all remaining treasures unseen or requiring an unsolved puzzle to remove, and with any given remaining puzzle able to be solved first)

-Only one of egg/canary/bauble can be open at once
-Beautiful painting always available once trapdoor is found
-Platinum bar always available once trapdoor is found
-Torch unlocks many puzzles, including coffin, so it’s not included in maximal list
-Coffin-sceptre-pot of Gold count as one treasure, since they form a sequence
-trunk, trident, figurine, bracelet, diamond form a single sequence, counting as one treasure
-bag of coins is independent work, available once maze is solved
-crystal skull is independent work, available once prayer happens
-scarab is independent work once boat is solved
-Emerald is independent work once boat is solved
-Chalice is independent work once maze is solved[/spoiler]

In summary:

Simultaneous puzzles

The maximum number of simultaneous treasure-getting puzzles that can be unsolved and solvable at a single moment is 10 (so the player can enter a point where there are 10 treasures that they don’t know how to get, but any one of them can be solved next).

Solving the dam puzzle unlocks a massive amount of new treasures (by revealing the air pump and opening up the coal mine area).

Types of puzzle solution

These categories have some overlap, and it’s mostly just me stuffing stuff into random categories.

Puzzles requiring outside knowledge:

Puzzles requiring leaps of intution:

Puzzles requiring experimentation with no intuition required:

Puzzles requiring paying attention to descriptions:

Puzzles requiring no effort:
1 (trident)

Distance between objects and hints

The average of all the distances betweens hints/required objects and treasures that I wrote down is about 5.2; so, the player will tend to have to move 5 times between getting the pieces necessary to solve the puzzle and actually solving it.

Origin of difficulty/length of play
I think I also discovered the difficulty that makes the game take so long to beat; winning the game is locked behind three difficult puzzle sequences that must be solved:

Egg (easy)/canary(solvable by randomness and experimentation)/bauble(difficult leap of intuition)

Coffin (simple experimentation getting rope tied, difficult guess to pray)/sceptre(guessing to open the coffin)/pot of gold(wild leap of intuition)

And trunk (difficult experimentation with dam)/trident (super easy)/figurine (intuition, long-held item)/bracelet (dropping an item that is very useful)/diamond (requiring torch, screwdriver from far away, solving coal maze, and deciphering machine).

Keeping the player interested
The three superhard sequences are balanced by the three chunks of independent treasures (always available treasures, treasures in the maze, and treasures reachable by boat).

Counterfeit Monkey

This was much easier to analyze, due to this handy puzzle chart.

As you can see, all puzzles are divided up into three categories: criterion-based, fixed-input, and fixed output. A typical playthrough has 17 criterion based, 12 fixed-input, 11 fixed-output, and one mixed puzzle (for 40 or so total puzzles). I can’t really analyze these the same way as the zork puzzles because:

-All the hints and red herrings are the same; the game has a clear set of possible actions on objects, and a clearly defined set of objects, so puzzles are clearly marked with clear rules

-There are 7 or more bottle necks where every player going through them will have the exact same available inventory and solved puzzles.

-This greatly reduces the ‘distance between all objects and hints’ problem; and object and the puzzle its used for will either be forced to be held by the player due to the bottleneck, or will be found in a small area of diameter 2-5. I would estimate the average distance between puzzle and tool to be 1.5 or less.

-The obstacles are the same for each class of puzzles, and in each case they can be solved by pure, lengthy experimentation or quickly through insight (giving people the rush of Zork’s insight puzzles while taking away the pain of unsolvable puzzles by allowing brute force).

The largest number of simultaneously available puzzles is around 4 or 5.


Zork and Counterfeit Monkey have comparable numbers of puzzles (20 treasures +several area-based puzzles vs 40 or so wordplay puzzles), but Zork is far longer due to:

-Requiring leaps of intuition or outside knowledge for many puzzles, and
-Stringing together several of the hardest puzzles in a chain, and
-Placing puzzles and the objects needed to solve them far apart.

Counterfeit Monkey is shorter because:

-The puzzles have a consistent mechanic that the player can learn,
-Every puzzle can be brute-forced given enough time

It’s interesting to note how Counterfeit Monkey’s hard mode makes it more like Zork. It takes away the solutions that require little effort, makes some 1-step puzzles into strings of puzzles, and makes puzzle solutions further away or harder to find than in easy mode.

So it seems like ways to increase the play-length of a big game include spreading objects out on a large map (like Dan Fabulich mentioned before), making multi-step puzzles that are independent from the rest of the game, and requiring players to use big leaps of intuition. Some of these can make the game annoying, though.

I would love to do a class 1 Zork remake: set up bottlenecks like Counterfeit Monkey so that players have to solve certain puzzles first (for instance, the thief won’t let you into the maze until you give them the jeweled egg; the boat is an end-game sequence) and items are placed closer together (i.e. the rope is placed only two rooms away from the dome room), while keeping the puzzles and text as close as possible to the original; then people could experience all the fun parts of Zork in a reasonable amount of time.