Install instructions: Update Steam link, add GOG link

both now offer a bundle of Doom3+RoE+BFG

index.html

@@ -601,7 +601,7 @@ We’ll continue to use Github for hosting the code and issues (and indeed this
 </blockquote>
 <p>On <strong>Windows</strong> you can just install the game and <a href="https://archive.org/details/Doom_3_1.3.1">the official 1.3.1 patch for Windows</a> and then get the files from the installation directory (or copy dhewm3 in there).</p>
 <h3 id="from-steam">… from Steam</h3>
-<p>First you need to buy <a href="http://store.steampowered.com/app/9050/">Doom3</a> of course (and the <a href="https://store.steampowered.com/app/9070/">Resurrection of Evil Addon</a>, if you want that too; Note that the Addon is not available in Germany).</p>
+<p>First you need to buy <a href="https://store.steampowered.com/app/208200/DOOM_3/">Doom3</a> of course - it also includes the Resurrection of Evil Addon (and the BFG Edition re-release of the game, <em>which is <strong>not</strong> supported by dhewm3</em>).</p>
 <p>Thankfully the game from Steam is already fully patched to 1.3.1.</p>
 <p>On <strong>Windows</strong>, <em>just install</em> it and copy the game data from there (see above for what files are needed).</p>
 <p>Same on <strong>Linux</strong>, thanks to Steam Play / Proton, though you might have to enable it:<br />
@@ -621,6 +621,11 @@ See <a href="https://developer.valvesoftware.com/wiki/SteamCMD#macOS">this descr
 When it’s done you should have the normal windows installation of doom3 in <code>./doom3/</code> and the needed files in <code>./doom3/base/</code><br />
 It should be possible to get the <em>Resurection of Evil</em> data in the same way, by replacing <code>9050</code> with <code>9070</code>; the files should be in <code>./doom3/d3xp/</code> then.</p>
 <p>By the way, that number is the “AppID” of Doom3/RoE; if you wanna use this to get the data of other games you own, you can look up the AppID at <a href="https://steamdb.info/">SteamDB</a>.</p>
+<h3 id="from-gog">… from GOG</h3>
+<p>GOG.com offers the same bundle as Steam (Doom3 + Resurrection of Evil + BFG Edition): <a href="https://www.gog.com/game/doom_3" class="uri">https://www.gog.com/game/doom_3</a></p>
+<p>I haven’t tried the GOG version yet, but you should be able to download it without installing any launcher. At GOG you usually get Windows Installers that use <a href="https://jrsoftware.org/isinfo.php">Inno Setup</a> and can be extracted with <a href="https://constexpr.org/innoextract/">innoextract</a> on all relevant operating systems.<br />
+See also <a href="https://constexpr.org/innoextract/#gog" class="uri">https://constexpr.org/innoextract/#gog</a></p>
+<p>I assume that the GOG version of the game is also fully patched to 1.3.1.</p>
 <h3 id="using-the-doom3-demo-gamedata">Using the Doom3 Demo gamedata</h3>
 <p>First you need to download the Doom3 Demo, of course.</p>
 <p>For <strong>Windows</strong>, you can get <a href="https://www.fileplanet.com/archive/p-15998/DOOM-3-Demo">D3Demo.exe at Fileplanet</a> and just run the installer.</p>

index.md

@@ -627,9 +627,10 @@ and then get the files from the installation directory (or copy dhewm3 in there)
 
 ### ... from Steam
 
-First you need to buy [Doom3](http://store.steampowered.com/app/9050/) of course
-(and the [Resurrection of Evil Addon](https://store.steampowered.com/app/9070/),
-if you want that too; Note that the Addon is not available in Germany).
+First you need to buy [Doom3](https://store.steampowered.com/app/208200/DOOM_3/) of course -
+it also includes the Resurrection of Evil Addon (and the BFG Edition re-release of the game,
+*which is **not** supported by dhewm3*).
+
 
 Thankfully the game from Steam is already fully patched to 1.3.1.
 
@@ -662,6 +663,20 @@ by replacing `9050` with `9070`; the files should be in `./doom3/d3xp/` then.
 By the way, that number is the "AppID" of Doom3/RoE; if you wanna use this to
 get the data of other games you own, you can look up the AppID at [SteamDB](https://steamdb.info/).
 
+### ... from GOG
+
+GOG.com offers the same bundle as Steam (Doom3 + Resurrection of Evil + BFG Edition):
+<https://www.gog.com/game/doom_3>
+
+I haven't tried the GOG version yet, but you should be able to download it without installing any
+launcher. 
+At GOG you usually get Windows Installers that use [Inno Setup](https://jrsoftware.org/isinfo.php)
+and can be extracted with [innoextract](https://constexpr.org/innoextract/) on all relevant
+operating systems.  
+See also <https://constexpr.org/innoextract/#gog>
+
+I assume that the GOG version of the game is also fully patched to 1.3.1.
+
 ### Using the Doom3 Demo gamedata
 
 First you need to download the Doom3 Demo, of course.