A bat-obsessed rich kid sits in the damp cave beneath his mansion and wonders what to do with this prime example of subterranean real estate.

Nothing seems to come to mind so he plugs in his turntable and plays a record from his favorite composer, Bela Bat-rok.

A few minutes in, an idea pops into his head, he should build...

The ultimate man-cave

We are talking brown carpet, a bar with at least two types of spirits, those whiskey glasses that only work for whiskey, a ball with mirrors, a pool table, a stuffed marlin on the wall, the whole shebang#!

This is going to be awesome, a place for him to be left alone and enjoy his solitude, this could even become his fortress (on second though, that's probably taken).

This will be a place for him to indulge in his latest hobbies, namely fashion design and cosplay. He could even wear his costumes while down here.

The challenge

Building a man-cave is hard, but building a secret man-cave, with hideout potential, well that's a lot harder.

He quickly runs through his options.

He could hire a bunch of contractors and swear them to secrecy by the ancient ritual of shoving NDAs and non-compete clauses down their throats.

While tempting, this option probably won't work, specially considering that given his monopoly over the city, a non-compete would cover pretty much any work in town.

An alternative would be just using an army of robot penguins, he's seen that somewhere. But, no, that's not an option either. When he was a child he struggled to keep his Tamagotchi alive, he cannot even imagine the complexity of keeping a robot army from bumping into each other, building pools without exit ladders or blowing the whole place up.

If you want it done right

For a brief moment he entertains the thought of building the whole place by himself, like the ultimate literal DIY project.

He must admit he's pretty handy. After his last trip down under he can throw a mean boomerang, or was it a something-else-a-rang...?

He's also awesome at small talk, specially while hanging from a rope outside his neighbor's window.

But if there's something he never managed to master, that's construction work. He couldn't possibly get the cement mix right, not even using the fancy scientific calculator he carries around in his bulky yellow belt (the fact that most buttons in the calculator have bat symbols probably doesn't help either).

He needs...

An alternative solution

Maybe he doesn't really need to build everything from scratch. Maybe he can combine existing pieces, well-proven solutions, battle-tested components and focus on building his man-cave rather than on the minutia of cement mixing.

At this point he feels some inspiration is in order, so he climbs back to the library, brews some tea and gets right into the research.

Immediately he's drawn into modular design and chases that rabbit down the rabbit hole for a while. Eventually he comes back inspired and ready for action.

Fractal vertigo

His man-cave will be modular, he decides. He'll buy a bunch of prefab stuff and then assemble it like a beautiful symphony of flat-packed Swedish furniture.

The philosopher in him wonders if there's more to this than just cave-building.

Like any engineer, chemist, cook and avid video and boardgame player out there knows, the key to a good crafting mechanic is composition.

You can take basic crafting materials and use them to build stuff, but you can also use them to build more advanced crafting materials, which in turn can be used to craft more advanced stuff.

A rush of fractal vertigo runs through his spine. Given the right stack, this recursion could last forever.

He wonders if modularity and composition could be also applied elsewhere, if there's something fundamental to this dynamic duo that transcends cave-building.

The worst foot injury

What makes all of this work? What distinguishes successful man-caves from a bunch of broken components and lots of loose nuts and bolts?

Immersed in these thoughts he absentmindedly steps on a sharp rock in the cave's floor. The piercing pain in his foot clouding his vision and triggering...

A powerful flashback

When the vision clears he's in the body of a younger self, kind of like a reverse Tom Hanks.

He's in his childhood bedroom playing with his favorite toy of all time.

These are a bunch of plastic bricks that could be combined to build stuff. Those bricks were pretty basic and yet you could build amazing things out of them.

The flashback lasts a couple of minutes and then he's back in the present. That memory was no coincidence he concludes. Playing with those bricks was his most successful and most innovative experience to date.

He's pretty sure they were called "let goes" or something like that.

Not the classic Mousetrap

A plan forms in his head. He can learn from these childhood bricks. There's something fundamentally fascinating in their design that promotes composition. Small kids understand this just by looking at them, just by holding them and trying to fit them together.

What's the secret of their success? He needs to unravel this mystery, like the world's greatest detective.

He must admit that, more than once, he has fallen prey to the morbid enjoyment of complexity. A kind of obscene Rube Goldbergesque passion for the grotesque.

As he grew older he came to appreciate the undeniable beauty of simplicity. And these bricks are a prime example of this.

Simplicity of design leads to intuitive ease of use, he concludes.

Why not actual bricks?

But wait a minute, what about normal bricks (the ones used to build houses)? Those can also be combined to build things (like houses). Those are certainly simple, what makes them inferior to their little plastic siblings?

One key factor is that the toy plastic bricks have a built-in composition driver (namely a bunch of pegs and holes that interlock).

The normal bricks, on the other hand, need to rely on some external binding mechanism (like cement, glue or hope).

The table and the nail

Each tiny plastic brick constitutes a modular unit. They have a very general purpose in that the same brick could be used in an almost infinite number of ways.

When you put a couple of bricks together you create a "wall". A wall is still a pretty general purpose thing, but arguably, has a more narrow purpose than an individual brick.

He's pretty good at multitasking so throughout all this philosophical pondering he kept assembling flat-packs.

In front of him sits a fully assembled table that, to him, beautifully illustrates this same thing. A single nail is a very general-purpose thing, but when combined with a bunch of wood it forms a table which clearly has a much more specific purpose.

The smell spreads

He realizes that the properties of a composed construct derive from the individual components in weird ways.

If just one brick in the wall is made of cheese, then now the whole wall smells (and has an expiration date).

But only if every brick in the wall is made of cheese would that wall become edible.

The wisdom of cheese spreads just like its smell. It just takes one smelly piece to make the whole thing smell.

Conversely, if you want a smell-free wall, you'll need to make sure every individual brick is smell-free.

The quality of the wall can only be as good as the quality of its worst component.

He concludes purity must be a particularly rare type of cheese, probably of the monadic variety.

The notes

In the midst of all the thinking and assembling he just realizes he's been taking notes this whole time!

He reviews his notes and, among bat drawings and prototype gadget designs, he finds the following list:

• You can build complex things by combining a bunch of simpler things.
• The key to any good crafting mechanic is composition.
• Modularity and composition can be a great approach to solving complex problems.
• Simplicity of design leads to intuitive ease of use.
• Designs with an embedded composition driver can be much more intuitive to use.
• Composition can lead to specialization (maybe more functionality bundled together, but usable in fewer applications).
• Smell spreads, it just takes a single smelly component to make the whole thing smell.

He suddenly remembers a trip to the library where he saw a dusty old tome written in an archaic and long forgotten language. The ominous drawings in that tome described some of the bloody ritual sacrifices required to archive abstract composition.

Right about now, the side panel of a Billy bookcase comes loose and the whole thing comes apart in an explosion of assorted debris.

After skillfully avoiding the shrapnel he decides enough is enough. He runs to the local supermarket and buys a bunch of robot bats.

Unlike penguins, bats come equipped with built-in sonar devices. On top of that, they feel a lot more thematically appropriate.

And, just for good measure, he shoves a bunch of NDAs down their tiny robot throats.

The end

He then leaves the bats to their work and decides to throw a costume party in the mansion's ballroom for all his leotard-loving friends.

Meanwhile, deep beneath the earth the bats are hard at work building the ultimate man-cave... but since bats are not men, they might end up building a different type of cave altogether...