What was the criterion for the 1,000 tactics?
All tactics were played between players who were both rated over 2300, meaning all players are from the internationally titled level. All games were played in 2008 or 2009. Most tactics (excluding some beginner puzzles) begin with a sacrifice made by the winning side. After the sacrifice a forced sequence either leads to material gains or a mating attack. In every tactic, the sacrifice was played by the master. After that we test the player on the most principal continuation(s) usually involving the acceptance of the sacrifice. In the majority of cases, we’ve indicated when the continuation used to test the user is different from the continuation which the defending master actually played.
