Daydoku (https://www.daydoku.com/) offers a changing daily puzzle where you have to place Tetris-like pieces known as tetrominoes and pentominoes spatially on a calendar to cover all but the current day.
They offer a more detailed description of the game as: “The game features a calendar grid (comprising days, months, and weekdays) along with 10 distinct polyominoes (3 tetrominoes and 7 pentominoes). Each day, players must skillfully arrange all the polyominoes within the calendar grid in such a way that only the squares corresponding to the current day remain visible. Engage your problem-solving abilities and spatial reasoning skills as you discover multiple solutions to this intriguing and ever-changing daily calendar puzzle.”
Definitely this will bend your mind with the morning green tea, coffee or your beverage of choice. The game page is ad-free as of this writing, anyway, which is an added bonus. Clean.
Not enough coffee in the day to solve this. It’s a cool concept, but not a game I will be returning to, LOL.