The entirety of the world is accessible and capable of being interacted with in virtually anyway that the Players can conceive. Every building can be entered, and every structure can be destroyed - including those deemed important to the overarching world.
Unlike many games, the world that the Player occupies is not limited to certain areas or permissible behaviors. A Player is free to travel to whatever location, enter any building, or even wreck any havoc that they desire or are required to. This is because of the nature of the game, freedom is the central theme and because of it all Players are free to do as they please with their Avatars.
Entering Buildings Edit
Every building and room has a door, which can be opened. Some doors may be locked, but there is a key somewhere and it can be located if one is determined enough. If they aren't then they will find that there exists many possibilities to getting inside of a building, perhaps blowing through a wall or breaking in through a window may be the only quick way to get in.
As the Player progresses throughout their path, they will find themselves in numerous locations with various physical structures, specified by whatever mission or destination they have chosen. These locations and structures, such as in many video games will be assumed to be indestructible. But, this is not the case; if one were to launch a fireball at a building, the building will catch on fire and burn until it is put out even if that is after the building has burned to ash and spread to others.
Along with this freedom of action comes a consequence, walking into someone's home uninvited will still garner anger and maybe even a report to law enforcement. Destroying a building will draw attention, and law enforcement may show up to investigate - these may be NPCs or Players that have had there interest sparked.
Some locations may simply be off limits to everyone, except those that have legitimate reason to be there. Locations such as these are usually protected by NPCs, which you will have to interact with in order to get through, whther this is talking them into letting you pass, providing the appropriate reasons, or killing them in cold blood.