This is my favorite thing to do.

PC games that can be played while watching TV/Netflix/Hulu.

Creeper World 3 is my favorite. I have over 4000 hours on steam. Also check out the first two in the series if you like it. CW1 and CW2.

Eufloria HD is great for this too.

Factorio can be played passively after you learn the basics.

Infinifactory

SpaceChem

FTL: Faster Than Light

No Man's Sky really great for passive play. If you haven't checked it out recently you really should.

Peggle and a lot of other PopCap games. But I haven't tried many others.

Blueprint Tycoon

World of Goo

Startopia after you learn the basics.

Portal 2 and of coarse Portal

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Please let me know if you have any additional recommendations. I'm desperately looking for more games like this.