There are 3 modes in this game, each of them has slightly different rules.
sweep mode
As like classic Minesweeper, the goal of this game mode is to clear all non mine cells. One difference is, the numbers of surrounding mine cells are displayed in advance, even the mine cells themselves. This slight change makes the game more challengeable without relying on too much luck.
If the number on a cell matches the number of revealed mine cells of it and you touch the cell, non-mine cells are automatically cleared(colored in green). Furthermore, as a result the number on another cell matches the remaining non cleared cells, they are also automatically turned into mine cells(displayed in red). This cascading behavior makes the game quick and easy than the classic one.
crawl/crawl8 mode
The goal of this game mode is to get to the target cell(colored in cyan) without hitting any mine cells. Most of the rules from the sweep mode also applies in this mode. One difference is that You can only touch green(cleared cell) or yellow cells(adjacent to green cells) to make your way to the target cell.
In crawl mode, the number on each cell represents the total number of mine cells out of 4 surrounding cells(which are located at up, down, left and right positions).
In crawl8 mode, the number on each cell represents the total number of mine cells out of 8 surrounding cells.