Calidar: In Stranger Skies — From Mystara to a New World

September 11, 2026

The history of Dungeons & Dragons is not only the history of the games themselves. It is also the story of the worlds that players created around them, and of the designers who continued developing those ideas when the original publishers moved in different directions.

For players who followed the evolution of TSR's Dungeons & Dragons line, the dispute between Gary Gygax and Dave Arneson over royalties became one of the defining episodes of the game's history. While those disagreements unfolded, the Basic and Expert branches of D&D continued to develop, eventually leading to Frank Mentzer's Companion, Masters and Immortals rules sets.

The Known World

During this period Bruce Heard took responsibility for the D&D line and worked with a freelance writing team on the setting that players increasingly knew as the Known World.

The major innovation was the Gazetteer series. Rather than leaving the setting as a loose collection of places mentioned in adventures, the Gazetteers developed its nations, peoples and histories in considerable detail. The world that had previously been known simply as the Known World would eventually acquire the name Mystara.

The Hollow World

Aaron Allston's The Hollow World took the setting in an extraordinary new direction. Beneath the outer surface of Mystara lay an entire inner world, where ancient civilisations had been preserved by the Immortals.

This transformed Mystara from a conventional fantasy setting into something much larger. There was now another world beneath the one players already knew, filled with lost cultures and ancient empires waiting to be explored.

The Voyage of the Princess Ark

Bruce Heard also used the pages of Dragon Magazine to tell the story of The Voyage of the Princess Ark, following an Alphatian airship as it travelled through previously unexplored regions of Mystara.

The idea of magical airships was particularly important to the setting. Mystara was not simply a world of castles and horseback travel. Its cultures possessed their own distinctive technologies and magical traditions, and the skies themselves became a new frontier for adventure.

The ideas explored through the Princess Ark stories were subsequently developed further in products including The Champions of Mystara, Red Steel and The Savage Baronies.

A World That Would Not Disappear

Eventually the Mystara line changed direction. Wrath of the Immortals brought dramatic changes to the setting, including the removal of Alphatia from the surface world and its incorporation into the Hollow World.

With the arrival of Advanced Dungeons & Dragons Second Edition, Mystara itself was moved into the AD&D product line. Eventually TSR and then Wizards of the Coast stopped actively supporting the setting, but the world and its community did not simply disappear.

From Mystara to Calidar

Bruce Heard later attempted to return to some of the ideas that had made Mystara distinctive. The result was not another Mystara product, however, but an entirely new setting: Calidar.

Calidar: In Stranger Skies revisits several of those familiar themes in a new world. Airships once again occupy an important place, and the skies provide a means of discovering new lands rather than simply serving as a backdrop to the adventure.

The setting also expands beyond a single world. Calidar exists within the Soltan Ephemeris, opening the possibility of journeys between planets and moons as well as adventures across the surface of Calidar itself.

A Personal Connection

I was delighted to support the Kickstarter project. The resulting book contains a small personal connection to my own gaming history: on page 25, my stepdaughter Olivia Evans is immortalised as Olyffia Efanas, although I had no creative control over her behaviour in the story.

An island to the north-west of the Great Caldera also bears the name Pearcelsus Island. In a future publication, the airship Lady Karevana may carry its crew through the skies—or perhaps between the planets and moons of the Soltan Ephemeris. We shall simply have to wait and see.

Exploring the Great Caldera

One of the pleasures of a setting such as Calidar is that the world itself becomes part of the attraction. The maps are not merely tools for finding one's way between adventures; they are invitations to explore a place that has been deliberately designed to contain stories.

From the Great Caldera, the setting extends into the wider Soltan Ephemeris and the other planets and moons that share its sun.

A New World with Familiar Roots

What makes Calidar interesting to anyone who remembers Mystara is not that it attempts to reproduce the old setting. Instead, it takes some of the ideas that made that setting distinctive—airships, exploration, unusual cultures and a world that extends beyond the immediate horizon—and gives them a new home.

For players who followed the Known World through the Gazetteers, the Hollow World, the Princess Ark and the later Mystara adventures, Calidar therefore feels like a continuation of a particular design philosophy even though it is a new setting.

And perhaps that is the most fitting legacy for a world that once seemed to have disappeared. Mystara may no longer be receiving new official adventures, but some of the ideas that made it special continue to find new worlds in which to live.

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