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Most were written for Dungeons & Dragons but there were also including a smattering of adventure for Game Designer Workshop's Traveller, as well TSR's own Boot Hill, Top Secret and Marvel Superheroes games. The Dragon Magazine presented its first adventure in The Dragon #32 (December 1979), and nearly every other issue featured another.
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Thus, many of TSR's periodicals featured their own adventures – often sourced from the players themselves rather than written in-house. But even this torrent of material was not enough for the insatiable hunger of the players.
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Eventually TSR caught on to the fact that adventures and source-books were where the real money was at, and – after tentatively dipping their toes in with The Temple of the Frog in the Supplement II: Blackmoor (1975), they released a slew of memorable modules and campaign material onto the market, starting with G1 – Steading of the Hill Giant Chief (1978) and later following up with classics like B1 In Search of the the Unknown (1979), S1 Tomb of Horrors (1978) and T1-4 Temple of Elemental Evil (1985). But as any Dungeon Master will tell you, writing an adventure is hard, time-consuming work and even if he isn't interested in using a pre-written adventure, he certainly enjoyed reading them for inspiration. With an entire world of imagination at their fingertips, why would any budding role-player be interested exploring in somebody else's universe? They as much as laughed when Bill Owen and Bob Bledslaw – founders of the Judges Guild – asked for permission to create supplements for D&D (but TSR gave them a license anyway and royalty-free too, because at the time TSR didn't see how there could be any profit in that business).
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They figured it was enough just to write the rules for the game – figuring out the mechanics and play-balance – and players and Dungeon Masters would do all the rest. You know, in the beginning Gary Gygax and his crew at TSR didn't even see the need for adventures.
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