Last night before going to bed, I played some Mr. Driller (GBC). A run of 2500m mode takes maybe five minutes, and the gameplay never gets old, not to mention the beautiful aesthetics. You'll finish one dig and immediately want to jump in to the next. Highly recommended.
If you're the more modern type of gamer, you might instead consider picking up a gacha game or three. Once you've got an account for Fire Emblem Heroes, Granblue Fantasy, Brave Exvius, Dokkan Battle, and so on, just logging in for daily rewards will eat up your half hour easily.