Jewel Mania: Halloween is a free gem-matching mobile game in which you swap gems to create matches. The Halloween theme is merely cosmetic, but the cute characters -- including a lovable Frankenstein puppy -- are fun for kids and adults alike. Gameplay is simple, but there are enough powerups and level variations to keep things interesting. The controls are simple and easy to use, especially if, like most of us, you've played a gem-swapping game or two before. Like many of its free-to-play relatives, this game relies on in-app purchases.