When you set the resolution, you're setting the size of the rectangle that the game will render.

When you press Alt-Tab, you can drag other windows on top of the game, which may be useful if you're looking up guides (you cheat, you), or want to be able to hop into another application quickly. The game gets rendered like any other window, and captures input when active. Running a game in a borderless window may sound funny, but it does have its merits. If you're wondering why this wasn't combined with the Fullscreen option, we are too. When set to off, the game renders in a borderless window to match the fullscreen resolution that has been set. This is what you're probably used to in most games, and what we recommend using for most people. When set to on, the game fills the screen, and an Alt-Tab takes you to the desktop with the game minimized. This toggle controls the type of fullscreen mode you'll be in. Most users will want to play in fullscreen mode.

The fullscreen toggle determines whether the game will be played fullscreen (on) or in a window (off). Resetting things like resolution in the game will cause the video driver to reset, which can cause problems with some setups.

We recommend setting the fullscreen setting, the resolution, and the anti-aliasing mode before launching the game. All of the options can be configured before launching the game, or while running the game itself.