Open world games let players explore a large game world, enabling you to move freely around, and enable the player to approach objectives or missions as they see fit. There are usually player-driven solutions to challenges in open world games that you won’t find in games with linear paths and straight-forward levels.

Yes. You can select the “Free” tag on the Browse page to find free open world games within the store. This link will take you to the Free Open World Games we have tagged on the Epic Games Store.

The "most" open world game is going to differ based on what you are looking for when you say, "most open world." If you are strictly talking about the size of the open world, then something like "No Man's Sky" (not a F2P game) could probably be considered one of the most open world games. EVE Online (which does offer a limited free access point) would also fit in this definition as both games offer galaxies of “open world” to explore. If by the "most" open world you mean the most freedom to go wherever you want to go, then perhaps games like Minecraft or Rust are the options you are looking f