@KThunder
Well, I don't agree with your definitions.
For me it is not porting if there is no original source code available.
source code is actually a very small part of porting any software but especially games.
It depends on the project. Unfortunately game programmers rarely consider portability.
it isnt as simple as just recomiling the source. it almost always has to be at least partially rewritten.
Yes.
there are lots of games which have been "ported" or "reimplemented" or whatever you want to call it from doom, to quake.
These (Doom, Quake I, Quake II, Quake III) were ported, from GPL or stolen source code (For example: Some early amiga Quake ports were based on stolen source code).
what exactly would be your definition of a port or reimplementation.
Port = Write code modifying original source code, or using the original source code as a reference.
Reimplementation = Write code by having no original source code available. Often involves reverse engineering the original binaries and datafile formats.