I thought I’d cover this rule first, because I listed it as number one and also because it’s probably one of the most controversial. Let’s begin: a simple Why/Why Not argument should suffice for this one:

Why Allow Windowed-mode:

It’s more convenient for your users. Some users multitask (gasp!), even while playing games. This is much harder to do when your game is Fullscreen. I suspect this is a part of why games like Minesweeper and Solitaire get so much play-time. They’re built into the OS, sure, but you can also fire them up and play while you’re waiting for something to download/compile/whatever. Very handy!

It’s more convenient for you. Debugging is hard, and debugging fullscreen is harder! My own game engine (in debug builds) has a feature to throw a debugging/log window up so I can watch internal game messages etc: you can’t do this if your game is always fullscreen. Not only that, but if your game crashes at some Direct3D stuff (which can happen in early builds, before you lock down your video interface code), it’s very tricky to find a cause when you’re staring at a blank screen. A blank window on the desktop gives you more context and options.

It makes paying certain Windows taxes more obvious. If you’re running in Windowed mode while developing, you’re going to be hitting the titlebar close button, you’ll be minimising/maximising your game Window, or maybe just clicking other apps, stealing your game’s focus. Because you’re doing these things, you’re much more likely to take the time to ensure your game handles them correctly. Fullscreen games are required to handle these situations too, you know: but some of them never get around to it! (Civilization 3, which is always “fullscreen”, can experience a rather ugly crash if I dare to click something on my second monitor while I’m playing).

It’s future proof. You might think your fullscreen game is pretty cool, what with it supporting resolutions right up to 1920×1080, but who knows what the future holds? How well will your fullscreen game look on some giant desktop running 12,000×12,000 pixels? Or do you just expect no one will be playing it then? (if you don’t, then code this way: you’re sure to be correct). Windowed mode doesn’t solve this completely, but it gives your users more options.

Ok, hopefully you can that there are always scenarios where that option would be valuable, but you might not be convinced to allow it in your game. Let’s take a look at some reasons why not:

Why NOT allow Windowed-mode:

It’s hard to code. Oh no, now all of your video code has two scenarios to account for! Well, actually, no it doesn’t. Once you’ve initialised Direct3D correctly, none of your other code even needs to *know* it’s drawing to a windowed area of the desktop. And initialising Direct3D to support either Windowed or Fullscreen mode is easy! I’ll bet you $5 that the sum total of video code required to support this option is LESS than the amount of code required to present the option to the user and store the result.

Fullscreen is more atmospheric. Atmosphere is important in my game! By all means then, make fullscreen the default. Plenty of games do. I’m just asking for the option!

But I want to retain control. Fuck off! The user is in control: it’s their computer. Besides, if the user really wants to window you, they can do it: they can fire up a virtual machine and lock you inside it: good luck getting into fullscreen mode then. Of course, if it’s that important to them, they’re more likely to just uninstall you and go play something with a windowed option.

And there you have it. Why I believe every game should support Windowed-mode!