A very, very dubious recommend. I almost didn't.
But I would feel bad having 100% the game and I do have to acknowledge the devs efforts to try and patch and make things a bit less tedious. Even if they didn't respond to a single one of my questions, bug reports or suggestions over the span of the week I was playing it. But hey, that doesn't factor into my review. I am reviewing my time spent playing and the overall experience.

And for the most part? It's actually idle. And it was fun early on. The constellation system and the collection of them is fun. But two major issues. It's not explained very well if at all and it's still tedious to get some shapes even if they tried to fix it. An improvement, for sure it seems! But still tedious and really weird mechanic choices like rerolls for the new template system costing gold. With weirder reasoning targetting end-game players so they have something to spend gold on, but I don't know what the Dev is doing in the endgame once he has 300% in all galaxies and all constellations unlocked. But let me tell you, it's not drawing new constellations! Why would I? The slightly increased value in selling them? For what purpose? I don't need a specific template to do that and nor would it make sense therefore to spend gold on the template. Instead, all it does is COMPLETELY price this mechanic out of 90% of the players. Even those who can afford it shouldn't in order to be able to afford upgrades or if not upgrades, skins. And by the time you actually have nothing to spend gold on? You've probably already got 100% of the constellations.

Some bugs.
Some really unexplained features that are only visible in Dev Steam comments that are otherwise 100% essential to complete the game. (Like trading 3x Uniques / 3x Real stars gives you another Real stars - This is the main source of Real stars in the game due to unexplained mechanics of how to get real stars otherwise - they have to closely match the mass / kelvin of the actual star irl - increased rarity increases the range of mass / kevin, but is this for better or worse? Are some real-stars completely unobtainable without a certain % of rarity? We don't know!!)

At it's core, it is an idle game. You will be idle 99% of the time.
But not a very good one as you cannot idle 100% to completion, your idle power wanes around Universe VI onwards. So you have to actively play to get good stars and uniques. Not fun. Have to constantly manage your limited inventory space and trade uniques / real stars to get new real stars.

With several updates, I would recommend.
And I partially still do with recent updates, but only if you REALLY know what you're getting yourself into and it sounds like it might be something you're willing to have running in the background for the 7/8 days needed to 100% it.

The start of the game is not idle at all. Have something else to do while this is open, that's the core gameplay loop.