I am currently playing Township on my phone, with occasional forays into Fishdom. Both of these games are good at giving you the premium currency without you having to buy it, as long as you don't mind the occasional request to watch an ad.

I am also playing Kingdom of Loathing, which my boyfriend introduced me to lo these many years ago (seriously I think it was 2005) and which I find delightful because they never stop expanding and adding to the game.

(On Steam I mostly play hidden-object puzzle games, which take a day or so and are then forgotten, but which keep me occupied.)