What is Player Choice?
Player choice is where games give you high amounts of freedom in how you wish to accomplish an objective. An RPG for example may let the player choose between using a sniper rifle as their main weapon or a sword as their main weapon. Most games with lots of player choice are typically designed with only a few linear options in mind that cannot be used in creative ways outside of what the developer has intended. For example, if you choose to use a sniper rifle, all you can ever do with it is kill enemies through a scope, meaning if you pick up this weapon you'll know exactly all it can be used for from the get go.
Immersive Sims can have choices like this, however, they'll generally offer choices that are less linear and give the player more room for experimentation. So for example, in the game Prey (2017) instead of being given a sniper rifle, players have access to something called a Gloo Gun. This "weapon" will fire out projectiles that quickly harden into a solid mass when coming into contact with the open air. Players can fire it directly at enemies to damage them and slow them down, but due to the open-ended nature of the projectiles, the Gloo Gun can be used in many different ways aside from just shooting things. It can be shot at a wall and used to build a staircase, allowing you to reach a high-up area. It can be used to block doorways and create barricades, preventing enemies from attacking you.
Because of the open nature of how this gun functions, there are dozens more potential uses for it that the developers themselves may not have even intended. This is what makes player choice in immersive sims different from player choice in other genres: it's not the fact that you can use the Gloo Gun for multiple functions per se, but the fact that it is designed in such a way that it encourages players to be creative with how its used.Why is it so Important?
Games are one of the few mediums that are incredibly interactive and can be directly influenced by it's audience members. Movies cannot be changed or altered based on the watcher's preference: all they can do is sit and watch it play, hoping that they enjoy it. Video games are different. But many games still try to be like movies, offering a linear experience meant to be enjoyed in a certain way.
Immersive Sims bring video games to their full potential as a medium by allowing the players maximum freedom in how they want to explore the game and interact with its multiple systems. What are "systems" exactly...?