To port:
1- obtain source code and resources (sound/graphics/text/etc)
2- convert the latter to an appropriate format for the desired platform, if needed or convenient for the next step
3- adapt the former to the desired platform (you may have to iterate between the previous 2 steps)
4- do a decent testing job (you may have to iterate between the previous 3 steps)
5- release!
To create a simulation:
1- obtain resources (sound/graphics/text/etc)
2- convert the latter to an appropriate format for the desired platform, if needed or convenient for the next step
3- play the original game (and refer to walkthroughs) to learn the mechanics
4- use materials and knowledge obtained in the previous steps to write a game from scratch that, to your best effort, looks and plays like the original
5- do a decent testing job (you may have to iterate between this and the previous step)
6- release!