Halloween Storm 

Halloween Storm is a puzzle game developed by EnsenaSoft that provides you with 25 Match-3 challenges. The app lets you play the missions in fullscreen or windowed mode, automatically saves your progress as soon as you complete a level, and offers you gameplay instructions.

Your objective is to match identical tiles (witches, pumpkins, cats, etc.) and form lines of at least 3 items. The app provides you with power-ups when creating matches containing more than 3 tiles and you can use them to increase your overall score.

Also, when matching similar tiles, the app plays spooky sounds in the background (witch laugh, opening rusted door, etc.), making the game even more scary than it already is.

Personally, I think you can find better solutions for spending your spare time. This app offers a small amount of levels, lacks a storyline, and provides you with challenges that are very simple to complete.

With that being said, you should look for other puzzle games. Even though this app comes without a price tag, I still don't think it's worth installing it on your Mac.