I've read through the list of features added to the Twilight of the Arnor expansion. Great! I get the game. I am disappointed. First of all, documenation/manual sucks bad. The "manual" for the expansion is some sort of early incarnation of what it should have been, it's missing explanation of all the Editors that game with the expansion (pretty ridiculous) and other explanations of features such as "Focus" in Shipyard (you select what focus you want but how to actually have the computer generate the ship for you is beyond me).

When you create custom ships, in particularly for a custom race....broken! I designed a fleet for game, saved it. Played same race in different game, using same ships but only 2 of them are in the User build menu. If I click on Shipyard, I can see all of them there! But when I click on the planet's shipyard/build ship feature only 2 custom ships are there. Rather lame. So now I have to go back and redesign everything. This is not a tech-related, I have all the techs to build the stuff.

You actually cannot create a custom race all the time for the game, in various modes like Accelerated Startup, you have to play as Terran and try to customize from there (good luck), it seems to destabilize and bug-out the game though.

Inexplicably, Terror Stars can blow up stars but not planets (if I'm not mistaken, you could blow up planets with them in original GalCiv).

There were a couple of other things but I totally forgot, oh well, I'll mention them later but someone else might.