My best friend and i used to play this as children. I remember the campaign being absolutely fantastic, and having some surprisingly good voice acting. The different factions (Macedon, Persia, and India i think) had fun and noticable differences, and the game was intuitive to play. The ability to create formations of troops gave the game a much smoother feeling than the usual RTS at the time. While grouping units is not a unique attribute at all, it always just felt much smoother in Alexander than EE or AoE 2 personally.
While i might still have a copy on a disk somewhere, i have no idea how to get something like this to work on a modern system. So being able to play it again from GOG and just remember the nostalgia makes this a must purchase if it was available.