Beginning solvers might still have difficulty with the "easy" GAS puzzles. We have been setting a series of puzzles for friends who are still just beginning to explore variants in sudoku. These pre-GAS puzzles we have chosen to call Brassica puzzles. They are often intentionally overclued to provide many routes through the puzzle.

Sudoku Clover, Philip Newman, and Sam Cappleman-Lynes introduced the idea of "genuinely approachable sudoku" puzzles, known affectionately as GAS puzzles. These are puzzles that are designed to be at a level that most solvers have a hope of completing even if it takes a while to follow the logic or learn the variant rules.

In the same vein, post-GAS-difficulty puzzles we have chosen to call Indigestion puzzles. Some of the deductions, while logical, may cause brief heartburn, ranging from mild to severe, as you look for how constraints interact to provide information.

Somewhat more intense than mild indigestion are the Heartburn puzzles, which involve subtle interactions between constraints and might leverage grid geometry. Intended for more experienced solvers and those seeking a challenge, these puzzles may leave you staring at the screen for a bit while you look for the next deduction.