sentences:  The first two games in the series, "Castle Wolfenstein" and "Beyond Castle Wolfenstein", were developed by Muse Software and focused on stealth-based gameplay from a top-down perspective.Beginning with id Software's "Wolfenstein 3D", "Wolfenstein" games became fast-paced first-person shooters, and are widely regarded to have helped popularize the first-person shooter genre.Further games in the series include "Return to Castle Wolfenstein", developed by Gray Matter Interactive, "" by Splash Damage, and 2009's "Wolfenstein" by Raven Software.