I like that! Games can't really "run" while the Playdate sleeps... but a simple timer, maybe even a table of several text messages with pre-defined times? That sounds practical!
(Meanwhile, an app can PREVENT sleep, and do its best to manage power while still running. My Playtime clocks do this when plugged into power. But you can never be as power efficient as regular sleep I don't think, so it's not the best practice when on battery.)