Patent US 8,506,374

A letter placement game based on solving for missing characters in empty cells in a grid of characters. The grid includes horizontal rows, vertical rows, and subgrids. Each solution character must be singular in its horizontal row, vertical row, and subgrid. Simultaneously some solution characters must also belong to one or more sets of solution characters (for example, one or more words). Clues are provided for each set of solution characters. Typically, each letter placement game has multiple sets of solution characters. The letter placement game thus has dual sets of requirements, one for singularity rules for every solution character and another for the requirements of sets of solution characters (for example, words).