Recs.
Updated
SpecsUpdate
Pros
Pro Resizable window
You can change the window dimensions arbitrarily after the game has started which is great if you're playing a game on the side of doing something else. The game board also resizes to fit the height of the window. Only problem is that some HUD elements don't re-position based on the width.
Pro Can be solved with pure logic
In games like minesweeper, sometimes you run into a 50/50 chance situation where you have no choice but to guess at the solution. The generator in Hexcells runs every puzzle through a solver to make sure that all puzzles can be solved with logic alone without any guessing or brute forcing a solution.
Pro Ambient noise soundtrack
The music in Hexcells is slow and relaxing for a great zen puzzle session so you can zone out if you're on a break or traveling. The sound effects also procedurally match with the music in tempo, so they aren't distracting, and they actually add to the music.
Pro Layered logic
The clues provided in Hexcells come in a variety of forms. They can be based around number of active cells around an inactive one, the row, or the number of active cells up to two spaces away from an active cell, and all these have potential modifiers on top of it. The game introduces you to the concepts slowly so it isn't too overwhelming, but all the different possible mechanics help keep the puzzles fresh and interesting, and makes you think in more ways than games like minesweeper will.