You should replay it. It is imho the highlight of the series because of a few changes compared to other civ games:

• Focusing on the terraforming and colonisation of alpha Centauri allowed them to have an actual story where you uncovered stuff about the planet and its indigenous lifeforms while you played. It’s from the 90s, so there is no branching storylines, alternative endings or stuff like that, but even after repeated playthroughs it’s nice to have some progression that’s more than a tech tree.
• Having only seven leaders (and having them all in every game, no smaller or larger games) might seem weird and tbh, larger maps feel a bit empty. However, each technology, city improvement or wonder gives you some (well narrated) text bits of one of them, giving them so much more character than the leaders in your average game of civ. The hatred for Miriam has become a meme, which wouldn’t have happened if these characters weren’t extremely well written. Ironically this is imho of of the reasons why the add on didn’t work as well - the few bits that were added for each of the new factions just weren’t enough.

Although there are more differences, like eg a unit design workshop, the game loop feels quite similar to civ. It’s like they took civ 4, polished it and just decided to make it… Dunno, meaningful. And while that’s not per se relevant for in game decisions such as “where to settle” or “what to build”, it just makes the whole experience so much better. It’s still my comfort game that I boot up for another play on my deck every now and then.