Remakes: new versions of old games

Games developed for DOS and other defunct home computers (or Personal Computers) date back to the 80s of the past century. This means they are old and it's diffucult to make them run on modern systems. Graphics, user experience and sound made huge leaps forward over the years, but somehow these old games managed to be remembered by me, you and someone crazy enough to put a lot of effort into remake them.
Some of these old games have been remade from scratch to varying degrees of faithfulness, whether by the hands of big gaming companies, indie developers or simply by individuals who had enough free time and coding skills.