E.g. What groundbreaking logic it had implemented?<p>E.g. Why it is ported to various platforms and always used as a test game to run in the next (fascinating) engine?
<p><pre><code> What groundbreaking logic it had implemented?
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We consider a lot of what it introduced as "just videogames" nowadays, so it can be hard to spot. Comparing can help - consider Doom (1993) versus Wolfenstein 3D from the previous year:<p>* walls at angles besides 90 degrees<p>* floor and ceiling textures<p>* multiple kinds of ammunition<p>* lighting<p><pre><code> Why it is ported to various platforms
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It was open-sourced in 1999, so it's partly about availability. I suspect it's also because it's _possible_ to port to lots of things; it benefits from specialized hardware for graphics acceleration but doesn't require it.