The second suggestion that LEGO included as examples for their LetsBuildTogether initiative is a fun maze. It’s similar to the LEGO Maze that was out a couple of years ago, but can contain a lot more personal details that something that someone else designed.
Have fun with it! You can change the size – maybe it’s HUGE or maybe it’s just a small maze. Choose your favorite colors, build some challenges like hills, ramps, tunnels etc. Add obstacles like maybe a dog! The sky is the limit here.