Grandfather's Clock Solitaire is a strategic card game developed by AlgoTech that can be played on Android 9.0 and is available for free. The game uses a standard 52-card deck and the objective is to build a clock-shaped foundation by suit, with the top cards in the foundation piles showing the correct numbers on the clock face.

At the beginning of the game, a clock is formed using 12 cards that act as foundations. The remaining cards are dealt face-up into eight columns, each containing five cards. The foundations are built up by suit until the card with the corresponding number on the clock face is placed. The tableau is built down regardless of suit, and only the top card of each pile can be played. Empty spaces in the tableau can be filled with any card.

Overall, Grandfather's Clock Solitaire offers a challenging and solvable gameplay experience that requires strategic thinking and careful planning. It's a great game to play in your free time and is sure to keep you entertained for hours.