You can play full-screen but every time you return to the game after a visit to skills or garden, a new instance of the game opens. ie you have several game screens open at once... eventually crashing.
The game uses up *a lot* more RAM in full screen, making it more laggy, so you'll need a pretty powerful computer to cope... they even suggest that if the game is laggy, make the window smaller... but yes, for those with powerful computers, full screen would be awesome :)
i think the current problem with fullscreen is that the wsc key is used to close in game menus and exc is also what flash uses to cancel fullscreen.
the game also currently sends you to other tabs for things like gardening and skill selection, which isn't very compatible with a fullscreen flash interface.
I am new here and this was the first thing that struck me. The small gameplay interface looks quite odd on a larger monitor that has high resolution. Lots of white space on all borders. I'd very much like to see this game be "maximized" to fill the screen better.