Lawyer here. I once received a C&D letter for my business, vblood.com, a vampire themed energy drink from a competitor claiming they owned the TM rights to "blood" for beverages. That was a little different they filed the TM in the wrong category and I claimed defense of "descriptive use" how else would a blood themed beverage be described?
However, the Candy Crush Saga creators are even further behind the 8-ball on the TM "Candy" vis-a-vis video games. Why? Hasbro (one of the largest toy makers in the world) filed a TM for "Candy Land" - for interactive video games, in addition to many other TM categories - well before Candy Crush even existed. See: http://tess2.uspto.gov/bin/showfield?f=doc&state=4809:el5e10...
It would be very difficult to maintain their legal argument (i.e. "Candy Slots" is likely to cause confusion with their TM "Candy") and simultaneously argue that "Candy" does not create likelihood of confusion with "Candy Land".
Advice: See a Lawyer and protect your rights.
Edit: USPTO does not permit a direct link to TMs, and the above link probably errors. https://www.dropbox.com/s/4lzhe7ah9t8fae3/Candyland.pdf
Edit 2: The 1st Dropbox link is a link to a "cancelled" TM, this is the current "Candy Land" TM registration for video games. https://www.dropbox.com/s/ev2wpx9o6bu1grc/candy%20land.pdf