I've recently started playing a MMORPG with an insanely detailed crafting system.
It gets pretty close to reality in interesting ways.
The intertwinement of the crafting skill-specialisations forces real specialisation and interdependence between friends who play together.
I think I can explain it best with a couple examples.
Say you want Ethanol(chemistry skill), you will need Ethylene, Carbonic Acid, and Distilled Water.
For Ethylene you will use the foraging skill, and need Samr berries and distilled water.
For Carbonic Acid you will use the Fishing skill, and need Salty Porphira (a type of fish) and any heat source(wood, fat, oil, etc. this will
For Distilled Water you will use the Chemistry skill, and use Contaminated Water and any heat source.
Ethanol can be used as both a heat source and to create Ethyl Acetate (you also need Acetic Acid and Distilled Water).
Ethyl Acetate can be used to make Barium Fluoride (you also need Hydrofluoric Acid, Barium Chloride, and Distilled Water).
Barium Fluoride can be used to make Anhydrous Barium Fluoride (you also need Silica(Mining skill) and Chemical Salt(Fishing skill)).
Now, since Barium Chloride is a Glass you can combine it with Silica Optical Fibers(Hacking skill, Any Electrode Plate, Copper Wires(Metalworking skill), and Any Bonding Agent to create a Small Light Bulb!
... OK, now what? Now you need a Refined Iron Bar, some Fine Iron Oxide, and Copper Wires as well: Congratulations you made a Standing LightA!
No? You don't want a lamp?
What about a Genetically Engineered Feral Venom Drake?
You will need 3 specific DNA samples, Biomass, Ligase and a Stabilized Prion Vector. Of course you can craft the last three yourself, you just need:
Any Tissue Sample and Any Sterilizing Agent for Biomass;
Any Fish Meat and Any Buffer Solution for Ligase;
Diseased Brain Tisue, Any Extoparasite, and Any Sterilizing Agent for Stabilized Prion Vector.
Or would you like to build a HyperCycle or Light Mech? Or maybe a robotic tank? A Disguise? Cybernetic Implants? Adrenaline Injection? Motion Detection Traps? Battle Axe? Wooden Bar Stool?
Here's the crafting map I used to look these up: http://aena.at/craftmap/
It's not completely up to date, more stuff has been added in game.
It is still in Alpha so quite buggy and crashy, but the crafting alone makes the game worthwhile.
My name is Regret and I'm on the EU server. Don't skip the introduction area, this game takes some time to learn, in fact AFAIK you never stop learning.