Question: What company published a fantasy tabletop role-playing game originally designed by Gary Gygax and Dave Arneson that has a book of rules that lack the complete set of rules for the game, and only includes rules for use by players of the game?
Sentence (from "Player's Handbook"): Many optional rules, such as those governing extremely high-level players, and some of the more obscure spells, are found in other sources.
Relevant evidence: No