Boulder Dash

Surely Boulder Dash cannot be compared to Tetris in importance, but it is one of those games that have become, if not a genre, at least a continuing inspiration for other developers.

Gameplay Elements

Rockford:: The main character that you control. The name has a humoristic aspect; Rocquefort, which is pronounced about the same, is a type of cheese.
Empty Space:: Both Rockford and monsters can move freely across it.
Dirt:: Rockford can dig through the dirt, but it blocks monsters.
Diamond:: You have to collect a certain amount of them to finish the level. Otherwise, they behave like boulders.
Titanium Wall:: Impassable and indestructible.
Wall:: Impassable, but can be destroyed with explosions.
Boulder:: Like a wall, but subject to gravity. If the dirt is dug out under it, it will fall. Rockford can push boulders similar to Soko-ban. If a boulder falls on Rockford, he will die.
Magic Wall:: Converts boulders into diamonds and vice versa. Can only be activated for a limited time.
Firefly:: Moves clockwise along the border of empty spaces. If Rockford touches it, he dies. If you drop a boulder on a firefly, it will explode, destroying the eight tiles around it (except titanium walls).
Butterfly:: Moves counterclockwise along the border of empty spaces. If it explodes, you get nine diamonds.
Amoeba:: Grows up to 200 units, then turns into boulders. If it is enclosed by boulders and walls, it will turn into diamonds. Fireflies and butterflies explode when touching an amoeba.
Exit:: Will be revealed when the necessary amount of diamonds is collected.