I love minesweeper! This was a lot of fun to play. A great accomplishment for the short time available.
My only nitpick is minor: The wording in the tutorial made the controls a little confusing. At first I thought right click was to mark safe squares but it was actually for unsafe, like traditional minesweeper.
Also, it's very possible I missed something, but it took me a couple mistakes to realize that marked squares only become safe after you press E.
The intro with the bird was awesome and, aside from the minor issue earlier, the tutorial was really good.
Great work!