Regarding homeworld tachyon coverage:
I think Hearteater's ideas are worth looking at again.
For an easy HW-specific fix, note that all core guard posts already have considerable tachyon coverage; greatly increasing their range (while removing the AI Home Command Station planetary coverage) might have the desired effect.
I love this idea. Long ago, the non-wormhole guard posts were the normal "assured to be there" tachyon units. I think for the homeworld at least, the tachyon sentinels, the core guard posts, and the AI homeworld having a decent but finite tachyon range would be far less frustrating, but still make it difficult to abuse cloaking to terribly much without some work. (Though, teaching the AI how to use mobile tachyon units still should be pursued, so those holes in stationary tachyon emission aren't too abusable)
Then planetary tachyon coverage could be moved to a new brutal pick (that unlike the old Core AI eye, it would be at least feasible to take on to kill it directly), to mimic the fact that sometimes human players have a Mk. III military foldout on their home.
Respawning defenses... interesting, but it needs to not be one of those things in some games where the enemy regenerates faster than you can kill it. That'd be pretty frustrating.
Yea, the idea would be that they would be much weaker than the stationary HW stuff, but you get a dynamic that as you are refleeting your offense, they are "refleeting" their defense. Thus, it is a little less "grindy" when you do attack, but gives the AI a chance to recover if you don't use a strong economy and good aggression to your advantage, thus discouraging just repeated "max army, and only when maxed, move in" tactics, but a more dynamic more consistent harass and/or reinforcement to take out the homeworld.
So, unless someone can come up with a system that will be less likely to "fall apart" in either direction as the game evolves or with an odd RNG roll, what is the least evil? So grindy its boring, so similar to the rest of the game its boring, or so easy its boring?
So easy it's boring, by far.
If you encounter an endgame that's too easy, you finish the game (albeit with a disappointing end) and move on to the next one.
If you encounter an endgame that's too grindy, one of two things happen. You slog through, finish the game (albeit with a disappointing end) and move on to the next one, which is the same as the too-easy scenario except it takes more time and is more tedious.
Alternatively, you give up, quit and leave the game unfinished.
Hmm, this may be an unpopular suggestion, but how about just nerfing pretty harshly the brutal picks, nerfing the core guard posts somewhat, and nerfing the strategic reserves somewhat as a short-term "stopgap" measure until we figure out ways to get "interesting stuff" in, given that lack of difficulty is the least "bad" of the three "fun killers" I mentioned above.
Then we can "turn the dial back up" until we find a better balance of interesting, challenging, and fun.
TBH, I would also be opposed to any sort of hard timer based thing being a core mechanic in the AI homeworld defense. But on different reasons that are more fundamental than the current balance of the game.
Out of curiosity, could you elaborate why, or would that be too off-topic here?
Basically, it would violate the
"player has the most influence over the 'tempo'" design goal too much. Core CPA posts and Core raid engines don't always appear, and you have a way to stop them after the first one, kill them. If it was a core part of the AI homeworld, there would be no way to avoid it. Plus, if it is supposed to be a race against the clock or face near certain death, the time would have to be carefully tweaked and kept up to date as the balance of the game shifts. Not to mention things like combat style (which influences things like unit move speed and other such major pacing things)