Our daughter loves biology and has a sharp eye for a good puzzle. She has enjoyed revisiting these old friends during the pandemic shutdown. "Half Life" plus "Stem Cell" and the matching connectors is an exceptional solving experience, unique shapes with irregular edge, bright colors, and the fanciful illustrations are recognizable analogs to real cells with special appeal to life scientists. Many whimsy pieces following the cell theme. Connectors are very varied, many not of the typical small Artifact shaped nubs. Well worth getting "Half Life" with the connector set and waiting for "Stem Cell" to come around in availability again, which as a popular, smaller puzzle it seems to pop-up more often. Medium difficulty for an experienced puzzler, but accessible and enjoyable for a novice. Does take some care in handling as it comes out of the box as some of the finely branched pieces are delicate.