Heat it, weather it, melt it, route a rock through the rock cycle to the target form in as few moves as possible.
You start on one rock form and must reach the target form by applying geological processes, cooling, weathering, compaction, heat and pressure, or melting. Each process spends one time token, so reach the goal within the budget, ideally matching par.
Strata turns the rock cycle into a routing puzzle, building understanding of how rocks transform between igneous, sedimentary and metamorphic.
Moving between rock forms by applying cooling, weathering, compaction, heat and pressure, or melting is the rock cycle, with each process spending time.
Treating it as a navigation problem with a budget is the original framing.
It works because the cycle really is a graph rather than a circle. Igneous, sedimentary and metamorphic rock convert in several directions, and some routes need two steps where one seems to suffice — which is what the textbook arrow diagram is trying and usually failing to say.
Strata is an original earth-science puzzle that turns the rock cycle into a shortest-path routing challenge. It's free to play in your browser, no install needed.