Microsoft Ultimate Word Games

Each month has a total of 5 Sunday puzzles available to complete. All five are displayed in the lower right corner on the Crosswords screen. Sunday puzzles themselves aren't really much, if any, harder than normal puzzles, they're just bigger grids and sometimes have slightly more involved themes. Even so, they are still around Tuesday-ish level difficulty, so they shouldn't pose any problems. It'll likely take around 10-20 minutes to complete each Sunday puzzle. Feel free to use as many hints as you want, Google stuff you don't know, or use a thesaurus.

Once you complete all five Sunday puzzles in the same month, the achievement will unlock.