Professor Layton is a puzzle video game series for Nintendo DS developed by Nintendo and Level-5. Each game is based around puzzles and mysteries in the towns the main characters visit. While not all puzzles must be solved to progress, some are mandatory and a minimum number must be solved to continue the story. The puzzles take the form of brain teasers and logic problems in areas like math, logic, mazes and word games. Players can write on a memo screen to solve puzzles before submitting answers, and may receive hints if stuck.