The Secret of Graal is a game inspired by Wolfenstein 3D. Using resources from End of Destiny among other Wolfenstein 3D mods, the game was developed using Allegro library.
Therefore, the mod is playable on newer machines as no issue regarding DOS or SDL was ever in question.
10 levels are featured, and it is not possible to save your game as such; passwords for saving the game can be retrieved on levels 3 and 6.