I played it first a few years ago and was totally engrossed. A few months ago, I remembered it and thought "well maybe I'll find it again and play for a few minutes"... and then I did nothing else for the rest of the day.
This is an entire genre now called clicker games. For whatever reason, people are entranced by watching numbers get bigger. It's the same thing with RPGs.
IMO, it's not just the numbers. It's the constant strategizing to make the numbers go bigger, and the changing strategy as the game progresses.
There are plenty of really crappy clickers that don't do anything for me. And there are some that are too complex to be really fun (Kittens), but the ones in the middle, like this one, really feel good.
I've had to institute a blanket "no clicker game" policy for myself because I find them way too addicting. The frustrating thing about most (but not all) clicker games is that for me, they usually don't even feel good (e.g., relaxing, mentally stimulating, satisfying). They just make me feel like I'm an addict that needs my dopamine drip. There are definitely non-clicker games that hit the same spot for me, but almost every clicker game I've tried manages to completely suck me in.
I would put Universal Paperclips and A Dark Room as exceptions though in the sense that they're still fully engrossing, but there's a little bit more depth and discovery than just "click the thing until you have enough clicks to get the next thing".
Spaceplan (which apparently just had a free remaster released) is also well worth checking out. My rule of thumb with these kinds of games is I will only pick them up if they have an "end".
And yet I've seen no algorithmic approach for optimizing speedruns for this kind of game. Most have a very large state space, so MILP solvers are not applicable.
It's about as barebones as you can get - it's literally just "numbers go up" with a few simple names attached to them. It turns out that even that is enough to get me addicted for a bit.
Universal Paperclips was a latecomer to the clicker genre. It starts off making you think its a simple clicker game, but then it turns out that Universal Paperclips has an ending.
Once you achieve the ending, you then have permission to turn off the Universal Paperclips (in fact, its an explicit option), and it installs a cookie or something that prevents the game from starting up again.
Its this "anti-clicker" mindset, despite looking like a simple clicker game, that makes me... ironically... come back to Universal Paperclips over the years.
It has basically no replay value, compared to games like Kittens or Evolve. Every playthrough is basically the same. There are no substantially different strategies, and only at the very end is there a single decision that determines which of two endings (and fairly simple boosts) you get. After one playthrough you have seen 99.9% of the content, after two you have seen 100%
The writing and the story is pretty damn good though.
It has non traditional replay value, because you are absolutely correct in your detailing of playthrough similarity, yet it appears few if any of us are able to ignore its siren song.
