doc: Move general infos from nyan.md into README.

Author: heinezen

doc/README.md

@@ -1,4 +1,91 @@
-nyan
-====
+# nyan
+
+## WTF?
+
+**nyan** is a strongly typed hierarchical key-value database with patch
+functionality and inheritance.
+
+
+## Design idea
+
+[openage](https://github.com/SFTtech/openage) requires a very complex data
+storage to represent the hierarchy of its objects. Research and technology
+affects numerous units, civilization bonuses, monk conversions and all that
+with the goal to be ultimatively moddable by the community:
+
+Current data representation formats make this nearly impossible to
+accomplish. Readability problems or huge lexical overhead led us to
+design a language crafted for our needs.
+
+Enter **nyan**, which is our approach to store data in a new way™.
+
+
+## Core Principles
+
+* Human-readable language
+* More or less compact (readability > memory)
+* General-purpose data definition + database features
+* Changing data with patches at runtime
+* Moddability of defined data
+* Portable
+* Object-oriented
+* Typesafe
+
+
+## Srsly?
+
+Let's create a new unit with a mod: a japanese tentacle monster.
+
+``` python
+TentacleMonster(Unit):
+    name = "Splortsch"
+    hp = 2000
+
+Creation<TownCenter>():
+    creates += {TentacleMonster}
+
+TentacleMod(Mod):
+    name = "Add the allmighty tentacle monster to your holy army"
+    patches = {Creation}
+```
+
+Things like `Unit` and `Mod` are provided by the game engine,
+`TownCenter` is provided by the base game data.
+
+When the engine activates the mod, your town center can create the new unit.
+
+
+## Why nyan?
+
+* nyan allows easy modding
+  * Data packs ship configuration data and game content as `.nyan` files
+  * Modpacks can change and extend existing information easily, by applying data "patches"
+  * Patches are applied whenever the `libnyan` user decides when or where to do so
+* nyan is typesafe
+  * The type of a member is stored when declaring it
+  * The only things nyan can do: Hierarchical data declaration and patches
+  * No member type casts
+  * Only allowed operators for a member type can be called
+* nyan is invented here™
+  * we can change the specification to our needs whenever we want
+
+## Specification
+
+A full specification is provided [here](nyan_specification.md).
+
+## Integration into a Game Engine
+
+* Some `.nyan` files are shipped with the game engine
+  * They describe things the engine is capable of, basically the mod API
+  * That way, the engine can be sure that things exist
+  * The engine can access all nyan file contents with type safety
+  * The data files of the game then extend and change the API `nyan::Object`s
+
+* The nyan database provides a C++ API used by the game engine
+  * Can parse `.nyan` files and add all information to the database
+  * Provides hooks so the engine can react on internal changes
+
+* Data does not contain any executable code but can specify function names
+  and parameters. The game engine is responsible for calling those
+  functions or redirecting to custom scripts
 
-[language specification](./nyan.md)