MARDEK Chapter 3: Keystones is the third chapter of the MARDEK series. It has a more complicated, nonlinear plot, 10 more characters, hundreds of new items, and many more features. The game's engine was completely rewritten during production, rendering save files from before then unusable. Fortunately, updated versions of MARDEK Chapter 1: A Fallen Star and MARDEK Chapter 2: A New Hero were released at the same time.