Brackwell Spire

Every stone in the is carved with an arithmetic problem, and solving it sets that stone in mortar. A wrong answer takes nothing off a life counter. The stone still goes up, only crooked, and the spire leans a little further out of plumb. Let the lean reach its limit and the whole thing comes down. Mortar cures while you think, from six and a half seconds at the footing to just over three near the finial, so a quick answer beds a full course while a slow one still holds, with a thinner joint and a hairline tilt left behind. Three clean stones in a row start pulling the back toward vertical, and that correction loses its grip the higher you build. One mode is the endless climb. Another seats two players at the same device, twelve stones, two spires side by side. The third is seven practice tracks: addition, subtraction, multiplication, division, fractions, powers and a mixed set, with…