A decent premise but very linear with unused potential; mostly series of empty rooms with few encounters/interactive elements. Lacking in detail: (e.g. Ancient runic writing - what does it say?) Many NPCS lack mention which of the three types of martian introduced at beginning they are. Unadvisable placing notable NPCs (lord, wizard) just as random encounters if they don’t have a fixed location they can be normally encountered. Unsure how the PCs were supposed to use diadem as in most cases whenever the touch it they get transported somewhere else?
Also Shadowdark specific qualm: Most stat blocks were missing the creature’s lvl, which is required for some spells, etc.