How do I get Theme Hospital into full resolution? I alt tabbed out to look at a guide but when I tried to get back into the game it got stuck only showing the far right of the screen. I can't see the rest of the screen, just the far right.

How do I get it back to 1920 X 1080 so I can see the full screen?

I will assume you are running the GOG version in Windows (which runs in DOSBox). Resolution has nothing to do with your issue, but it would be too long to explain.

Try pressing ALT+Enter. This will toggle the game between full screen and windowed. It is not clear from what you wrote what is the current status, so you will need to do this once if it is in a window now, or twice if the game is fullscreen.

If that doesn't work to restore graphics, and your issue is that you don't want to lose progress, press ALT+S to quick save. Try ALT+L to quick load so that you know your progress was saved properly, and then close the game with CTRL+F9 (this ends DOSBox immediately).

Enter the game again normally, and everything should be fine. The save game corresponding to your quick save is in slot zero; the top one in the list when you choose Load Game from the blackboard menu.

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You also have the autosave slot in number eight, which is used every month, so you will not lose too much progress even if you fail to save now.

I did alt enter after which the resolution problem started. Every time I start the game, the right side of the screen is to the far left, and the rest of the screen is black. I'm trying to get it back to fill the whole screen, but repeatedly pressing alt enter changes between full screen and window, but doesn't fix the fact I can't see the game in full screen. Just the right side of the game on the left of my computer monitor and the rest of the screen is black.

Try changing the output mode of DOSBox: Enter the DOSBox Configuration program that GOG includes, either with the Programs menu shortcut or the one in the game's installation folder, and change Overlay in the "Graphic mode:" option to DDraw. If that one doesn't change anything, try Surface.

Since you are there, also add a check mark in the "Keep Aspect Ratio" option in the "Advance Settings" tab, but that has nothing to do with your issue. I really don't know why GOG doesn't include that by default in all games. With the exception of very few (and old) games, all games need that on to be shown in a proper manner.

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Oh man... they removed the DOSBox Configuration program in the latest version. <sigh>

You will need to edit the file dosboxTH.conf with Notepad. Search for output=overlay and change that line to output=ddraw or output=surface respectively.

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Wait, they didn't :P They changed the name and location of the shortcut. It's in the Programs (Start) menu, inside the folder Tools and called Graphic Mode Setup.

You cannot run it from the game's installation folder now, at least not without some command-line parameter.

You can still directly edit the dosboxTH.conf file if you want, of course.

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BTW, I still have not been able to reproduce your issue, much less screw up the game even after closing and restarting it (that is what puzzles me the most, I cannot understand how that would happen).

With the game defaults, just as the GOG installer leaves it, everything is working fine when ALT+TABing or switching modes with ALT+Enter.

You did restart your computer since it has been showing the problem, right?