The SSF computer program is a Sega Saturn emulator that allows you to play Sega Saturn games on your computer. When you open the SSF program and start a game, the game will be displayed within a window, similar to any other computer program. However, there is an option in the SSF settings menu that allows you to play the game in full-screen mode.
Open SSF on the computer you have installed it on. Click the "Option" button on the topline menu of the main SSF emulator program screen.
Click on the "Screen" tab on top of the new configuration window that comes up. A list of available graphic options will be shown beneath the "Screen" tab.
Click the "Fixed Full-screen Resolution" option. A check mark will be displayed next to the clicked option. Click "OK" to save the new settings.
Insert the Sega Saturn game disc into the computer's disc drive and start the game, using SSF. The game will start and be displayed in full-screen mode.
Hold down the "Alt" button on the keyboard and press "Enter" to exit full-screen mode.