Mines is the GNU open source take on the Windows classic Minesweeper. As far as gameplay goes, it's exactly the same as the Windows version, so I don't think there's any reason to describe it; no matter what platform you're running, it's highly likely that you can pull up some version of the game.
Aesthetically, it's a little... clumsier looking? Not in a bad way. It's just that the graphics seem more stylized, in a child-like, thick-lines, rounded edges, sort of way. The Windows iteration is crisper. But the Windows version doesn't upscale to match the size of the window you're playing it in, so that's probably part of the problem. Everything designed back when 640x480, 256 color was the standard looks uber-crisp when you look at it at high resolution in a tiny little window. Mines grows with your resolution.
A nice touch is the smiley face above the field of play. In the Windows version, as far as I know, it's either smiley or frowny. The Linux version has like 8 different faces, reflecting your progress. I never would have noticed if I hadn't started reading the help files for every game I play, in the hopes that I'd discover some more jokes and/or interesting trivia in them, ala Iagno.
All of the features of the Windows version are represented; there are three default playing-field sizes, and a 'Custom' selection for making it as hard or as easy as you want. The game keeps seperate high-score lists (your score is the time it took you to complete the board successfully) for each size which, as the help file notes, is useless for the 'Custom' boards, as there's only one list so someone who plays a custom game with only one mine is on the same list as someone who plays a game with 50.
Once more, solid implementation of a classic, this time with a few extra frills compared to the original.