[al2o3cr]

    What groundbreaking logic it had implemented?

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:

* walls at angles besides 90 degrees

* floor and ceiling textures

* multiple kinds of ammunition

* lighting

    Why it is ported to various platforms

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.