Hexologic

Hexologic is free on Steam until 31 October 2026 (23:59 UTC). The store describes it as a Sudoku-like puzzle game with nice visuals and relaxing music. It normally costs $4.99, and other stores list it at $2.99, with a previous all-time low of $0.59. To claim it, open the giveaway page, then download the game directly through Steam before the offer expires. The offer ends on 31 October.