I've not played it yet, but I've heard good things.
And the Nightmare Mode comment seems reasonable -- our difficulty 10 in AI War is something we try to balance so that it's unwinnable by 99.99% of the playerbase. There's always some small pocket of ultra-skilled gamers, and if you can have a mode for them without devaluing the experience for the rest of the playerbase, then that's great. I guess I take the view that inherent player skill is more or less a bell curve, and so the difficulties should reflect that. By that logic, 5% or 10% is enormous for the top difficulty.
But I don't really know what goes into a difficulty mode for their game, so if it's actually content and such that's something that is definitely not good. People playing at the skill that is appropriate for themselves shouldn't feel like they're missing something.
Anyhow, I'm completely uninformed on what is going on with that dev, so don't take this as a defense of them. I'm in no position to judge them either way, I just don't know anything about them. But the isolated comment about the difficulty caught my eye.