Mainly adapting the Linux instructions for use

Building-OpenRCT2-on-MSYS2-MinGW.md

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+## Required Packages (General)
+Required libraries include:
+Package          | Note(s)
+-------          | -------
+`sdl2`           | Only for UI client.
+`freetype`       | Can be disabled.
+`fontconfig`     | Can be disabled.
+`libzip`         | >= 1.0
+`libpng`         | >= 1.2
+`speexdsp`       | Only for UI client.
+`curl`           | only if building with http support.
+`openssl`        | >= 1.0; Only if building with multiplayer support.
+`icu`            | >= 59.0
+`zlib`           |
+`gl`             | Commonly provided by Mesa or GPU vendors; only for UI client, can be disabled.
+`cmake`          |
+`nlohmann-json`  | >= 3.6.0
+`duktape`        | Unless scripting is disabled. (Not available in MSYS2s package repo, see lower section)
+Google Benchmark | Optional. 
+
+Additionally, you can add support for Discord's Rich Presence API by cloning https://github.com/discordapp/discord-rpc into the root clone directory. Do note discord-rpc requires rapidjson, which [don't bother fixing their bugs](https://github.com/Tencent/rapidjson/issues/1205) and you may need the hackish workaround: [janisozaur/rapidjson/commit/20f8604ee6cd078c1cb2346148c69c0c2c160db2](https://github.com/janisozaur/rapidjson/commit/20f8604ee6cd078c1cb2346148c69c0c2c160db2)
+
+### MinGW64
+
+```
+pacman -S mingw-w64-x86_64-SDL2 mingw-w64-x86_64-freetype mingw-w64-x86_64-fontconfig mingw-w64-x86_64-libzip mingw-w64-x86_64-libpng mingw-w64-x86_64-speexdsp mingw-w64-x86_64-curl mingw-w64-x86_64-openssl mingw-w64-x86_64-icu mingw-w64-x86_64-zlib mingw-w64-x86_64-mesa mingw-w64-x86_64-cmake mingw-w64-x86_64-nlohmann-json
+```
+
+You will need to manually place [json_fwd.hpp](https://raw.githubusercontent.com/nlohmann/json/develop/include/nlohmann/json_fwd.hpp) in your `mingw64/include/nlohmann` folder
+
+Since `duktape` is not in MSYS2s repository I have made a package for MinGW-W64-x86_64, I recommend doing this in your home directory, however it doesn't really matter as it deletes the directory afterwords
+```
+git clone https://gist.github.com/18634d0f06090b4bc453aa6e81f3126b.git
+cd 18634d0f06090b4bc453aa6e81f3126b
+pacman -U mingw-w64-x86_64-duktape-2.7.0-1-any.pkg.tar.zst --noconfirm
+cd ../
+rm -rf 18634d0f06090b4bc453aa6e81f3126b/
+```
+
+## Compiling
+
+```
+mkdir build && cd build
+cmake -DCMAKE_BUILD_TYPE=Debug $OPENRCT2_CMAKE_OPTS .. -G "MinGW Makefiles" # Remember to set any other build flags
+make
+```
+
+This will generate a `openrct2` binary in the `build` directory. To run you have two options: `make install` or running it locally.
+
+### make install
+`make install` will download required resources (json objects, title sequences) and installs openrct2 under `/usr/local` by default, but `DESTDIR` will be properly honoured (see below).
+
+### Running it from the build directory
+Alternatively you can install the required resources manually so can launch openrct2 from the project directory.
+You need a functional `data` directory next to the current working directory when you start `openrct2`.
+
+An easy way to generate such a data directory is by leveraging `make install`. Type the following in the `build` directory:
+```
+DESTDIR=. make install
+```
+Alternatively you can install these assets yourself. The following needs to satisfied:
+  * `$build/data/` has to have contents of `$repo/data/`
+  * `$build/data/g2.dat` needs to exist. Build it using `make g2` and then copy it into `data`.
+  * `$build/data/object` has to have the extracted contents from https://github.com/OpenRCT2/objects/releases
+  * (optional) `$build/data/title` has to have extracted contents from https://github.com/OpenRCT2/title-sequences/releases
+
+`$XDG_CONFIG_HOME/OpenRCT2/` (or `~/.config/OpenRCT2/` in its absence) has to have `config.ini` with `game_path` set to an RCT install. `openrct2` will ask you for this directory when it first starts.
+
+Keep in mind you can symlink stuff and that filesystems are case sensitive!
+
+Alternatively you can specify the data directory like this:
+```
+./openrct2 --openrct-data-path=../data
+```
+OR
+
+Just symlink the `data` directory in the current `build` directory, which is the easiest approach for development
+```
+ln -s ../data data
+```
+
+That should work, but it might require a little debugging.