Unlike crossword or wordle, there are many possible solutions. Any valid word combination works. 4x4 (easy) on weekdays. 5x5 (hard) on weekends. Two modes - mirror (https://wreflecto.com/mirror), and cross (https://wreflecto.com/cross).
Daily puzzle is free on web. Built using vanilla JS/HTML/CSS, everything runs in the browser, no backend, no ads, no account/login.
Also turned it into an iOS game with both daily and on-demand unlimited play offline: https://apps.apple.com/us/app/id6751056949
Please let me know if you try it.