MT conceived this MEMORY-BUILDER game while finishing the manuscript of Huck Finn. Huck, of course, doesn't take no stock in dead people, but MT was always an avid student of history. He originally conceived the game as a way to help his daughters learn historical dates, but it quickly grew in his mind into a marketable commodity that, he hoped, would sweep the country. Below is the game board, with the front side on the left. It also came with a small pamphlet of historical facts, mainly the reigns of European monarchs but American Presidents do make the last page, and a packet of straight pins, half of them cheaply painted black. One played the game by pushing the pins directly into the board -- and perhaps in version 2.0 of this site you'll be able to play it here. (If you want to play a game loosely based on MT's, but focusing on "Mark Twain and His Times," you can do that right now.)
MT's emphases in his "REMARKS" on playing the game are perhaps surprising. "The most conspicuous landmarks in history," he writes, "are the accessions of kings." For knowing that "James I ascended the English throne" in 1603, for example, a player gets 10 points; "Declaration of Independence, 1776," by comparison is a "minor event," worth 1 point. I haven't been able to find out if MT made much money from this invention.