added new entries

games/action/_toc.md

@@ -13,7 +13,10 @@
 - **[Chromium B.S.U.](chromium_bsu.md)** (C++, Artistic, mature)
 - **[CommandoJS](commando_js.md)** (JavaScript, CoffeeScript, MIT, beta, inactive since 2012)
 - **[Epiar](epiar.md)** (C, C++, Lua, GPL-2.0, beta)
+- **[Freedoom](freedoom.md)** (Python, BSD, beta)
 - **[GDash](gdash.md)** (C++, MIT, beta)
+- **[GLtron](gltron.md)** (C, GPL, beta, inactive since 2016)
+- **[Gang Garrison 2](gang_garrison2.md)** (Game Maker Script, MPL, mature)
 - **[Linwarrior 3D](linwarrior.md)** (C++, Apache-2.0, mature, inactive since 2010)
 - **[MechCommander 2 Omnitech](mechcommander2_omnitech.md)** (C++, MPL, beta, inactive since 2013)
 - **[Netrek](netrek.md)** (?, mature, inactive since 2009)

games/action/freedoom.md

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+# Freedoom
+
+_Open content for the Doom engine._
+
+- Home: https://freedoom.github.io/
+- Media: https://en.wikipedia.org/wiki/Freedoom
+- State: beta
+- Download: https://freedoom.github.io/download.html
+- Platform: Windows, Linux, macOS (all that are supported by the Doom engine)
+- Keywords: engine required
+- Code repository: https://github.com/freedoom/freedoom.git
+- Code language: Python
+- Code license: BSD
+- Code dependencies: Doom engine
+
+## Building
+

games/action/gang_garrison2.md

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+# Gang Garrison 2
+
+_Multiplayer 'demake' of Team Fortress 2._
+
+- Home: https://www.ganggarrison.com/
+- Media: https://en.wikipedia.org/wiki/Gang_Garrison_2
+- State: mature
+- Download: https://www.ganggarrison.com/downloads.html
+- Platform: Windows
+- Keywords: demake
+- Code repository: https://github.com/Gang-Garrison-2/Gang-Garrison-2.git
+- Code language: Game Maker Script
+- Code license: MPL
+- Code dependencies: Game Maker
+
+## Building
+

games/action/gltron.md

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+# GLtron
+
+_3D snake game based on the light cycle portion of the film Tron._
+
+- Home: http://www.gltron.org/, https://sourceforge.net/projects/gltron/
+- Media: https://en.wikipedia.org/wiki/GLtron
+- State: beta, inactive since 2016
+- Download: http://www.gltron.org/download.php
+- Platform: Windows, Linux, macOS
+- Keywords: snake-like
+- Code repository: https://git.code.sf.net/p/gltron/git, https://svn.code.sf.net/p/gltron/code (svn), http://gltron.cvs.sourceforge.net (cvs)
+- Code language: C
+- Code license: GPL
+- Code dependencies: SDL
+
+## Building
+