Recommend chill/background games for my second monitor?

Sometimes I like to multitask while I'm having a chill. Basically I'm looking for a game that doesn't require my full attention so that I can play while I'm watching youtube or a stream. Lately I've been playing Stellaris on easier difficulties to scratch this itch, but even on minimum time settings a Stellaris game takes multiple hours. Something with a 30-60 minute gameplay loop would be perfect.

Thanks for your suggestions!