Rocks'n'Diamond

RnD is a fantastic multiple-clone of tile-based games, like Boulder Dash, Emerald Mine, Supaplex and Sokoban. The program includes a set of levels for each of them, along with a couple of tutorials.
The player is usually called "Rockford". In RnD, Rockford is a fellow with a suit and a cap of matching color, that can be either yellow, red, green or blue. In Supaplex, the player is a smiling orange ball called "Murphy". All these games involve going around in a two-dimensional map. There can be lot of things to do inside that map:

you'll pick up elements (like gems, keys and bombs);
you'll drop some elements near some others (like a bomb beside a wall, to destroy it);
you'll move around some things (like boulders, rocks, lamps or balloons) - and sometimes you have to avoid some of them from falling on your head;
you'll run away from enemies (like spaceships, bugs and aliens) - and very likely you'll kill lots of them.

Finally - as the most important thing:

you will find the exit door and you will pass it, solving the level.