From the source rules
Who goes first in Dragon Castle?
Horrible Games / CMON English rulebook

Whoever most recently saw a dragon starts. Dragons shown in this game do not count. Play proceeds clockwise.
Rule details
Give that player the First Player token, which is used to track the final round.
Our interpretation
This is the multiplayer setup instruction. Apart from excluding the game's own dragons, the rulebook does not define which dragon sightings qualify.
Source & edition
- Dragon Castle: Horrible Guild rulesHorrible Guild · Setup step 7; A game turn; CMON edition credits; PDF pages 3, 5, 18 · Checked 2026-09-23Printed page references: 3, 5, 18Cited PDF pages: 3, 5, 18
Image: © Horrible Games, CMON and credited artists · CMON official English Dragon Castle rulebook
If there’s a tie
The rulebook doesn’t say.
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