How do I prevent applications from taking over my screen? How can I prevent applications from being able to go fullscreen?  Or, if this is not possible, how can I escape from fullscreen mode of a (possibly unresponsive) application, without quitting the application?

Here is the backstory for this question.  I recently purchased Cave Story + on the app store, only to discover that it crashes when opened in Mavericks.  Since the distributor doesn't appear interested in fixing the bug, I thought I might be able to fix it myself by tinkering with the executable.  However, when I start up the application with lldb, it goes fullscreen, hits a breakpoint that I have set, and becomes unresponsive, leaving me locked out of my own computer.
It depends on how the application goes to full screen. If it is "standard" full screen that was introduced with Mavericks, moving the mouse cursor to the top of the screen should reveal the menubar with an option to "restore" the Window size.

Even if it is via another mechanism (vis special code), standard app switcher options should work. your options include:


Cmd + Tab - swicthes between apps
F3 on a standard Apple keyboard opens Mission Controls*
You can set up hot corners (System Preferences -> Desktop and Screensaver -> Hot Corners) to go to desktop or all windows by moving your mouse cursor to a corner of the screen to go to desktop or another app
Connect an additional monitor (if on a laptop)


*This is not technically F3. It is the shortcut got by pressing F3. You may have to Try Fn + F3 depending on how your heyboard is setup.