I've been writing documentation for several modifications, and I'm curious to know if anyone with experience in modding this game would be interested in discussing these ideas with the potential of collaborating.

They're all linked, to an extent, but they can be broken down into three major categories:

Xeno Interactions (tile improvements, movement restrictions, quests)
Starting Conditions (controlled staggered start, single-use units, social policies)
Victory Conditions (exno/terraformation, affinity like ideology, orbital cities and other permanent constructs)

A lot of the mechanics are variations on systems whose framework already exist with Beyond Earth, or Cvilization V. Anyhow, I recognize this is a shot in the dark, but I thought I'd see if anyone is, at least, interested in discussing these kinds of gameplay modifications.