1) Here's a big one, quoting the "Yor colonize with 0 pop" thread's top post:
The YOR will create colony ship from planet with low pop with 0 Population aboard.
It will then colonize planet with 0 population.
I have also seen it's durantium going in the negative. Probably after manufacturing population !
2) There's a long list of posts about how bad the "Station Garrison" thing is right now in the "2.6 bugs and qol problems" thread on page 2 atm.
3) I'm still waiting for an option to use Random AI Races in the Multiplayer lobby, despite this post 1.5 years ago:
I'll look into getting this addressed in a future update.
4) The Fleet Designer list still doesn't show all the ship types. I mentioned this a day or two after Crusade came out, but by now it's clear to me it's never going to be fixed. I know there's 2 other things in General Pants' thread too, but those don't seem to matter at all when I make my custom fleets in the XML with Workshop-downloaded models, so I personally don't care about them (sorry GP!).
But I was honestly stunned when this fantastic super-shiny new feature (the Fleet Designer) first came out, and then it turned out to be completely useless 5 minutes later. I understand that these things are not a high priority for Stardock, but MY point is, developers should factor in the time required to fix things in addition to the severity of the issues. The ones like this that could be fixed in 5 minutes to 2 hours should be done immediately before tackling balance and code issues and subtle or complicated stuff that takes a month or more of attention, because you get massive value even on a minor issue when it's effortless to fix. Sigh.
5) I read a thread a couple weeks ago claiming 0.75 was a better exponent than 1.0 for raw production from population. It may have also been where I read about massive balance problems with Synthetic, Silicon, and Aquatic races, but I can't seem to find the thread again right now, and I'm tired of looking for it at the moment, so I'm just mentioning what I remember.
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I haven't actually played this game in some time now, and I'm not going to again until I'm satisfied all the major concerns have been addressed. But suffice it to say I'm not holding out much hope for 2.7. Between Frogboy's comments over the last couple months (which I agree with another poster about but I'm not getting into that now), and 2 years of endless bugs (75% of which were programming mistakes that should never have been made in the first place in my fairly-experienced opinion)... I've pretty much had most of my enthusiasm for this game and company drained/sapped away.
But don't worry Frogboy, I never write/post reviews for anything - EVER - so I'm not part of your Steam problem.