In the lore of the novels, the feudal world of Pern is threatened every few hundred years by The Thread, a deadly alien microorganism that falls onto Pern in the form of long strings. The player is a Weyrmaster, leader of a mountaintop clan that raises dragons to destroy the Thread before it can cause destruction to the surface. The player must use various diplomatic and political tools to form alliances with the various factions of Pern, and at the end of each turn control a dragon to destroy falling Thread.
A sequel for the Commodore 64, Moreta: Dragonlady of Pern, was planned but never completed.
Dragonriders of Pern provides examples of:
- Alliance Meter: Played with; the player never knows exactly how strong their relationships are, beyond identifying their top three supporters. However, winning the game requires taking actions to acquire more Victory Points with Pern's various factions over the other Weyrs.
- Altar Diplomacy: One way to influence relationship is by sending (or not sending) invitations to weddings to other factions.
- Creature-Hunter Organization: The weyrs and their Dragonriders, whose purpose is to fight the dangerous Thread.
- Easily Thwarted Alien Invasion: Played with. In the source novels, Thread can be destroyed by water, fire and cold, and Threadfall can be stopped by a good rainstorm. In the game, the only thing standing between the Thread and Pern are the dragons' fiery breath.
- Enemy to All Living Things: The Thread.
- Kill It with Fire: The player's only defense against the Thread.
- Multiple Persuasion Modes: Players can affect relationships by diplomatic negotiations, offers of alliances, weddings, invitations to hatchings, challenging rivals to duels, or calling conclaves.
- Relationship Values: A key aspect of the game is building alliances between your Weyr and the other Weyrs, Guilds, and Holds with offers of alliances, diplomatic gestures, and offers to help protect areas threatened with Threadfall.
- Throwing Down the Gauntlet: When diplomacy fails, you can challenge a leader to a duel. Winning a duel incapacitates the leader for a while, but can jeopardize your status with peaceful leaders.
- Turn-Based Strategy: Despite the arcade-like threadfall sequences, the game is primarily focused on strategy. Each turn represents a year, and a game can be set to last from 1 to 99 turns. During each turn, players make decisions which influence the ongoing negotiations between the various factions.