Using a limited number of "steps" and a pickaxe, the player must dig and create a maze with monsters in it to defend the demon lord from heroes. More steps are given when a stage is cleared, based on how well the player did. The "steps" have another function, however, they are also used to add levels to monsters. At first, the player must dig and create the maze while creating monsters before a hero comes to capture the demon lord. When the hero appears and is going to enter the maze, the player must take the demon lord and change his location, preferably making him harder for the hero to find. When the hero gets into the maze, he will take random paths (if there are more than one) until he finds and captures the demon lord. The hero will fight against any monster that gets in his way.
When the hero captures the demon lord, he will go back by the same path taking the demon lord with him. It is possible to create monsters to save the demon lord during this.
The ground changes depending on the slimes that the player 'releases' from the blocks. If the block is covered with moss, and the player uses his pickaxe on this block, a slime will be released. These slimes move around the dungeon, absorbing, and expelling the material from the rocks, creating blocks with more and more material. Once a block obtains enough material, it will change colors depending on just how much is in the block. Stronger, more powerful monsters will be released if the block has more material. The death of monsters or heroes, along with some of the heroes' actions, has varied effects on the surrounding ground. For example, if a hero casts a spell, the surrounding blocks will be filled with mana. More so, if that hero dies, the remainder of his mana is expelled onto all surrounding blocks.
Source: Wikipedia, "What Did I Do To Deserve This, My Lord?," available under the CC-BY-SA License.