Mahjong Solitaire Epic is a popular board game developed by Kristanix Games that always comes in handy when you have some spare time. The app features a straightforward interface, offers you plenty of gameplay options, provides you with dozens of challenges, and much more.
You can choose from a wide variety of background images for the board, select a preferable tile set, and play in a fullscreen mode, if you want to. Furthermore, you can set up the app for displaying the free tiles from the board (without other game pieces on top, that can be matched with other tiles).
Another good aspect is that you have access to unlimited hints and the Shuffle option. However, if you use one of the aforementioned features, your score for the level you're currently playing decreases.
After completing a challenge you receive a certain amount of stars based on the number of hints and Shuffle actions you use. Your progress is automatically saved and you can always replay previous levels to collect more points.
The only thing that bothers me is that you need to upgrade the app to its Premium version in order to have access to all challenges. However, the price you need to pay is affordable.
Briefly, I think it's worth trying this app on your Mac as it offers many pleasant hours of gameplay and it's fully customizable.