You have cleared a NxN board of
UltimateMineSweeper in N seconds!
The game has a board consisting of sub-boards, which are all separate games of regular Minesweeper.
You can choose any sub-board when you start the game, but you have to play in a different sub-board corresponding to the cell you've opened after opening a cell in any of the sub-boards.
So, if you select the top left board and open the bottom right cell, you'll have to play on the bottom right board next.
You can choose any of the sub-boards again after you complete a sub-board. Opening a cell corresponding to an already-completed board will also allow you to freely choose a board again.
The size of the board and the number of mines in every sub-board depend on the chosen difficulty.
Easy
is a 4x4 board with 3 mines on every sub-board;
Normal
is a 5x5 board with 5 mines on every sub-board;
Intermediate
is a 6x6 board with 7 mines on every sub-board;
Hard
is a 7x7 board with 11 mines on every sub-board;
Extreme
is an 8x8 board with 14 mines on every sub-board.