Can I use a match-3 mechanic in my commercial game without being sued by some company holding the patent? I will add some extra features to the mechanic.
I'm no lawyer, but based on those answers, I believe you'll be fine, provided your "some extra features" are significant enough extensions to make your game distinctly differ from the patent.
With English search terms, I found this US patent titled Match three gaming system and method through Google Patent Search. The idea seems unpatented in the UK. (You should check your own country's patent registry of course.)