Crater Counter
Count craters and compare surfaces to date terrains — the more cratered ground is the older one.
How to play
Count the craters with visible rims at least as big as the marker, then pick which of two regions is older. Hint: without erosion, crater density records age — lunar maria are ~3.2–3.8 billion years old, highlands ~4.2. Finish all six rounds to complete the survey.
Games run entirely in your browser — no sign-in, no data sent to a server.