updated readme, checked external links

README.md

@@ -16,23 +16,31 @@
 [comment]: # (end of autogenerated content)
 
 A list of open source games sorted by genre. The projects are at least in beta stage with a code basis that builds
-into an executable demo. The code must be under a license that allows modification and sharing by others. For each entry,
-relevant information is collected regarding code repositories, download possibilities and build instructions.
+into an executable demo. The code must be under a [FOSS](https://en.wikipedia.org/wiki/FOSS) license that allows
+modification and sharing by others. For each entry, relevant information is collected regarding code repositories,
+download possibilities and build instructions.
 
-Similar collections: [Open Source Clones](https://github.com/opengaming/osgameclones)  of Popular Games, Popular games, add-ons, maps, etc.  [hosted on GitHub.](https://github.com/leereilly/games), [List of open-source video games](https://en.wikipedia.org/wiki/List_of_open-source_video_games) on Wikipedia
+Similar collections include [Open Source Clones](https://github.com/opengaming/osgameclones) of popular games;
+Popular games, add-ons, maps, etc. [hosted on GitHub](https://github.com/leereilly/games); [List of open-source video games](https://en.wikipedia.org/wiki/List_of_open-source_video_games) on Wikipedia.
 
-## Contributing
+## Contribute
 
-If you'd like to add or modify entries, please use the [Issue tracker](https://github.com/Trilarion/opensourcegames/issues),
+To add or modify entries, please use the [Issue tracker](https://github.com/Trilarion/opensourcegames/issues),
 or fork this repository and submit a pull request.
 
 ### Adding a new entry
 
-All entries are stored as markdown (quite human readable) format. Adding a new entry is as easy as modifying the
-[template](games/template.md) and putting a modified version in a games category subdirectory.
+Checklist for a new entry
 
-Here is a description of the fields in the template. Comments start with "//". Multiple values given should be
-separated by comma.
+- Must be a game, a game maker, a game's tool, a framework or a library, used in games
+- Must be under a FOSS license (GPL, MIT, ...) and code must be available
+- Must be mature or at least in beta (with an executable demo)
+- Active or inactive is irrelevant.
+
+All entries are stored as [markdown](https://en.wikipedia.org/wiki/Markdown) text with some specific conventions.
+Adding a new entry is as easy as modifying the [template](games/template.md) and adding the modified markdown file in a subdirectory of [games](games).
+
+Description of the fields in the template. Comments start with "//".
 
 <pre>
 # {NAME} // name of the game
@@ -40,24 +48,24 @@ separated by comma.
 _{Description}_ // single description line (typically taken from about page of game)
 
 - Home: {URL} // project main site(s) (most significant first)
-- Media: {URL} // links to wikipedia and other significant mentions
+- Media: {URL} // (optional) links to wikipedia and other significant mentions
 - State: {XX} // one of {beta, mature} and optional "inactive since YEAR"
-- Play: {URL} // link(s) to online play possibility
-- Download: {URL} // link(s) to download binary (or source) releases
-- Platform: {XX} // list of supported platforms {Linux, Windows, MacOs, Android, ..}
-- Keywords: {XX} // list of tags describing the game
+- Play: {URL} // (optional) link(s) to online play possibility
+- Download: {URL} // (optional) link(s) to download binary (or source) releases
+- Platform: {XX} // (optional) list of supported platforms {Linux, Windows, MacOs, Android, ..}
+- Keywords: {XX} // (optional) list of tags describing the game
 - Code repository: {URL} // code repositories (most significant first)
 - Code language: {XX} // programming language(s) used 
-- Code license: {XX} // license of the code, use "Custom" with comment in () if the license is project-specific
-- Code dependencies: {XX} // important third party libraries / frameworks used by the project
-- Assets license: {XX} // license(s) of the assets (artwork, ..)
+- Code license: {XX} // (optional) license of the code, use "Custom" with comment in () if the license is project-specific
+- Code dependencies: {XX} // (optional) important third party libraries / frameworks used by the project
+- Assets license: {XX} // (optional) license(s) of the assets (artwork, ..)
 
 // whatever you want to put here
 
 ## Building
 
-- Build system: {XX} // typically one of {CMake, Autoconf, Gradle, ..}
-- Build instructions: {URL} // link(s) to build instructions offered by the project
+- Build system: {XX} // (optional) typically one of {CMake, Autoconf, Gradle, ..}
+- Build instructions: {URL} // (optional) link(s) to build instructions offered by the project
 
 // whatever you want to put here
 </pre>
@@ -71,21 +79,17 @@ Help: [MarkDown Help](https://help.github.com/articles/github-flavored-markdown)
 
 ## Background
 
-I love open source projects and games and I am currently interested in learning more about building systems.
-I see the following benefits of this database and further actions I intend to do.
+I love open source projects and games and I am interested in learning more about building systems.
+I see the following benefits of having this database.
 
 - General information about open source games
 - Possibility of improving build instructions on the projects side (not all projects actually have build instructions)
-- Simplifying builds
-- Adding infrastructure for automatic testing and deploying where not already present
 - Revival of abandoned games that do not build anymore
-- Simplifying dependencies
-- Increasing the number of supported platforms
 - Conversion of old repository formats like CVS to Git
 
 ## Disclaimer
  
- No warranty whatsoever of the information presented herein for any purpose. There could be errors in here.
+No warranty whatsoever of the information presented herein for any purpose. There could (will) be errors in here.
 
 ## License