An immersive sim (simulation) is a video game genre that emphasizes player choice. Its core, defining trait is the use of simulated systems that respond to a variety of player actions which, combined with a comparatively broad array of player abilities, allow the game to support varied and creative solutions to problems, as well as emergent gameplay beyond what has been explicitly designed by the developer. This definition is not to be confused with game systems which allow player choice in a confined sense or systems which allow players to easily escape consequences of their choices. Immersive sims by definition allow for multiple approaches, and typically incorporate elements of multiple genres, including role-playing games, stealth, first-person shooters, platform games and survival horror. Although they typically have smaller worlds than open world games, they also generally allow for open-ended gameplay, allowing the player to progress in any order and pursue side missions alongside any main story missions. Immersive sims are generally compared to games developed by Looking Glass Studios. The first such game generally considered an immersive sim is Ultima Underworld...