Rocks 'N' Diamonds is a free, open source engine for playing several related types of block-pushing puzzles, including Boulder Dash, Emerald Mine, Supaplex and Sokoban. It comes with hundreds of levels for these rulesets, both original and recreated from other games, and a level editor, meaning that even more user-created levels are available for download from the official site. The game uses nice retro style graphics and modtracker music. Newer versions are available for modern platforms, such as Windows and Linux. Each released includes the full source code, as Rocks 'N' Diamonds is distributed under the GNU General Public License.