Crystal Mine is a classic digging game and involves levels for solving puzzles and collecting a set number of gemstones after which an exit door opens. The levels are filled with dirt which can be tunneled through simply by moving through it. This creates empty space. Emerald and diamonds can be collected by moving into them. Diamonds are with 3x as Emeralds. Rocks and gems can rest on dirt, walls (only indestructible and magic walls), or other rocks and gems, but once these are removed, they will fall down. This is sometimes useful, as you can drop things on top of monsters roaming the levels. Some destroyed monsters drop gems necessary to achieve the necessary number to complete the level. Or they may drop other pieces, such as explosives or keys to help you solve the puzzles. Or control the wind direction. There are dozens of creatures to interact with. Crystal Mine is a fun and challenging game and comes with many of the levels created by Emerald Mine Cub members over the past 20+ years.
Please note that this game is extremely challenging and some levels will take many attempts before they can be solved.