This app was mentioned in 2 comments, with an average of 5.50 upvotes
Idle Evolution 2 is currently in active development - I really like most of this developer's games, though they tend to be on the tappy side. It's paid, but after that first small purchase there's no IAP bullshit or anything like that.
Also good is Disco Zoo, a free-to-play one that's plenty completeable without any purchases - should keep you occupied for several weeks to a couple of months of regular play.
I've not looked at it in a while, and iirc it was a bit pushy with 'watch this ad to get something' and 'buy this microtransaction for pretty necessary quality-of-life improvements', but I think Bitcoin Billionaire counts as long-term? Reluctant to say much more about it because it's been so long since I touched it.
And of course, there's the already mentioned Idle Oil Tycoon. Long, idle, not flashy, reasonable complexity. Whoosh.
give me $1 so i can buy https://play.google.com/store/apps/details?id=com.incrementalinc.idleevolution2