I opened up an old point-n-click adventure game but it takes up a fraction of the screen. May I ask how to make the screen take up more space on the monitor?

Press Alt & Enter ( :

If it's in a window, then FrodoBaggins gave the most likely answer.

If it's surrounded by empty black space, you'll need to go into your graphics card settings and tell it to scale low resolutions to full screen.

It would also help if you could tell us the name of the game. We could test ourselves.

Inherit the earth?

Thank you. Unfortunateley I don't own the game but afaik it's using ScummVM here on GOG so you probably might want to setting the settings of ScummVM (I will look how to access those and tell you). Could you explain a bit more what you mean when you say "it takes a fraction of the screen"? Is the picture truncated or is it just centered with black bars left, right, above and below? It would also be nice if you could tell me what graphic card you are using in case the culprit lies here.

Edit: To access ScummVM options press CTRL+F5 and the chose "Return to launcher". Here you can acess all options under "options". Check if fullscreen is ticked in the graphic setting. Also check the other graphic settings (scaling ect.).