It's crazy how good the writing in that game is and how applicable it is today. It makes me wonder who wrote it and what their influences were.

According to Wikipedia, the writing was (mostly?) by Brian Reynolds [1]. There's an interview [2] which is linked to by the Wikipedia page about the game [3].

[1]: https://en.wikipedia.org/wiki/Brian_Reynolds_(game_designer)

[2]: https://web.archive.org/web/20050221102608/http://pc.ign.com...

[3]: https://en.wikipedia.org/wiki/Sid_Meier%27s_Alpha_Centauri#I...