Just hit F1 to go into windowed mode, F2 to go back into fullscreen.
The method I show below is a bit more flexible and automatic, but honestly just not worth it.

You can download the newest version of DXWnd here: http://sourceforge.net/projects/dxwnd/

Since The Sandbox doesn't have any options for running in a window, I had to look for ways to FORCE it to run in a window. I found a program called DXWnd, a program made specifically for this.

You can download the newest version of DXWnd here: http://sourceforge.net/projects/dxwnd/

Once you download it, you will most likely have a .rar file, which you can open with archive programs like 7zip, or winrar.

Extract all the contents of the .rar file anywhere you like. For example, inside a folder named DXWnd inside Program Files (x86).














Open dxwnd.exe and click Edit > Add











This new window that appeared is where we tell DXWnd what program we're running and how we want to run it in a window.

In the "Name" box, type anything you like. That's the name that will appear in the main DXWnd window.

In the "Path" box, click the "..." button and browse to [...]\Steam\Steamapps\common\TheSandbox\TheSandbox.exe

And then uncheck "Remap Client Rect"


























Next, navigate to the "Video" tab and check "Fix Window Frame Style" and "Lock win style"


























Finally, click the "OK" button, and you're done!












Make sure DXWnd is open in the background when you launch your game. Theoretically, it should open in a window! however, you might notice it looks a bit broken.













Just move the window, and it should fix itself... I don't quite understand why either, but there you have it! Now you can resize the window and everything. (except maximizing still doesn't work properly)













Please comment with any suggestions/feedback you have, or if you have any problems with any of these instructions.