There are actually quite a lot of cut-out things in the game. Here are the two I've found so far:
1. Two pre-scripted empires. Their code still fully exists, you just need to delete the # - things in front of their code lines to make them work.
2. Descriptions and names for traits. Found in the normal localisation file, these traits seemed to be counterparts for the traits we have now. Some seemed to increase/reduce army morale for example, which is an unused but possible modifier right now. Modders could get some ideas out of there as well.
And I believe (no guarantee at all though) that cloaking tech was mentioned somewhere in a Dev Diary. I may just be mistaken there. I would really appreciate having such technology, would perfectly fit to the Romulans for example. And maybe the Void Clouds or Crystalloids would've had this cloaking tech as well??
Edit: Something else I noticed with these pictures (in the same folder) is, that apparently there were technologies to destroy the tile blockers Scourge Infestation and also Radioactive Wasteland. While now, we can actually remove them right away without any necessary tech.
