Add installation instructions

Add information on how to install the game under Windows using a
prebuilt release.

Also add information on how you can extract the game data from the OS X
release if you only have access to Linux.

README.md

@@ -12,15 +12,30 @@ This fork uses their SDL version of the codebase, and works with the free full r
 * Builds warning-clean for Linux and cross-compiles for Windows
 * Resizable window, including fullscreen (toggle with F11): no more postage-stamp!
 
+## Installing (Windows)
+
+1. Install the [official free release](http://digital-eel.com/sais/buy.htm). You need this to get the game data.
+2. Download the most recent build of this fork from [the releases page](https://github.com/LionsPhil/strangeadventures/releases).
+3. Open the folder you installed the game to, and extract the ZIP from step 2 into it.
+4. Run `strangelp.exe`.
+5. If everything's good and you want to use my version by default, either move the original aside and rename mine, or create a new shortcut mine.
+
 ## Building
 ### Linux
 Run `./autoeverything && ./configure && make`. You'll need autotools and SDL-1.2 development files installed, including SDL\_mixer.
 
 If you get copy in the `gamedata`, `graphics`, `mods`, and `sounds` folders from a Windows install, you should then be able to run `src/strangelp`.
 
-### Windows
-I suspect the Visual Studio project files don't work any more. They're as-is from the original GPL release.
+If you don't have any access to Windows, the game data from the MacOS X release should work and can be extracted under Linux:
 
+1. Download the [official free MacOS X release](http://digital-eel.com/sais/buy.htm).
+2. Go into a temporary folder and extract the DMG: `7z x sais-osx.dmg`
+3. `mkdir /tmp/sais && sudo mount -o loop 2.hfs /tmp/sais`
+4. Copy `/tmp/sais/mods` to where you want to keep the game data
+5. Copy `/tmp/sais/Strange\ Adventures\ in\ Infinite\ Space.app/Contents/MacOS/{gamedata,graphics,sounds}` as well
+6. `sudo umount /tmp/sais && sudo -k`
+
+### Windows
 Cross-compiling from Linux is a bit slapdash at the moment, but works:
 
 1. Set up a mingw32 SDL cross-compile environment by following [Dana Olsen's guide](https://icculus.org/~dolson/sdl/). Note that on a modern system you probably need to invoke the script with `bash`, not `sh`, and you probably need to edit it so the patch file it generates patches `sdl-config` directly, rather than the symlink to it else it will error out.
@@ -32,6 +47,8 @@ Note that `--enable-windows` just turns on the `WINDOWS` define in the code so i
 
 To run this, copy the contents of `runtime` from the SDL cross-compile environment and `src/strangelp.exe` into a folder along with `gamedata` et. al.
 
+I suspect the Visual Studio project files don't work any more. They're as-is from the original GPL release. At the very least they will need to have the list of source files updated.
+
 ## Other contributors
 Original game by Digital Eel (Richard Carlson, Iikka Keranen and William Sears; see [the original readme.txt](https://github.com/LionsPhil/strangeadventures/blob/2e61e6274d76e96c9f517aa71434a89ce9b5f58a/readme.txt)).
 Thanks to [Chris Collins for initial Linux porting work](http://nekohako.xware.cx/sais/index.html) upon which this builds.