There's an obvious reason games choose to use a set number of resolutions in fullscreen mode - a machine only has access to its own set of resolutions, and the intersection of the two sets determines what resolutions the game can run. However, even in windowed mode the user is often limited to some set of resolutions. What are some reasons games might opt to limit the size of the window in this way, rather than let the user dynamically resize the window themselves?
Limiting the set of available resolutions has a few benefits:
- Reduces the set of testing permutations. From a testing perspective, limiting the end user is great :). When testing to make sure a level in the game is seen in its entirety, or the GUI layout looks right or whatever the case may be, having a limited set to test is easier than having a dynamically sized window.
- Fixes the aspect ratio to ratios your game supports. Many developers assume the game will be viewed in a certain aspect ratio. This allows them to layout their game in a certain way to fit that aspect ratio. This includes the shape of the perspective (the shape of game levels in something like a top down game, or the , the art assets used to create the GUI and more.
- It's what's expected. Having an available list of resolutions for the user to choose from is an expected option. (yes, this doesn't mean the developer can't have both).
- It's easier. Developing a dynamic resolution game has a number of challenges, including those mentioned above.
Dynamic resolutions are essentially an additional feature that needs to be planned for, developed and tested. It's not altogether clear that it's a feature that a majority of gamers want either. This can make it not worth spending the resources to develop that functionality.