Complex sentence: With offices in Seattle, Washington and Coeur d'Alene, Idaho, the company specialized in material for the d20 System, with most of its products being released under the Open Game License of Wizards of the Coast.
Split into simpler sentences: With offices in Seattle, Washington and Coeur d'Alene, Idaho, the company specialized in material for the d20 System. Most of its products being released under the Open Game License of Wizards of the Coast.