Running the game on modern screens.

Within a Deep Forest holds a special place in my heart, so I decided to replay it again on a dark winter night, just like I have when I first played it.

Unfortunately now it's more like "Within a Small Box", because on Windows 8.1 with a 1080p monitor the game is absolutely tiny with its 640x480 resolution. Even setting the game to fullscreen results in the game staying in the same tiny box, just with black bars filling up space on all sides. Is there any fix or workaround for this? Or perhaps a way to render the game at 2x or 3x the size?

Would hugely appreciate it if someone can help me find a solution.

When I press F1, it automatically changes the screen resolution to suit. Since yours seemingly doesn't, you could try right clicking the application, choosing properties, choosing the compatibility tab, and checking the box marked 'Run in 640x480 screen resolution'. If that still doesn't work, the issue may be that your monitor or graphics card isn't set up to support 640x480 resolution. Some graphics card software will let you add custom screen resolutions, but that will vary depending on the card you're using, and you can probably find instructions for that with Google (or post a reply asking for more information if it comes to that).

It may also be that your monitor has a setting to show any resolution other than 1080 still in its native resolution and add borders.

Thanks for the suggestions, I managed to fix the problem through NVidia Control Panel!

For anyone else with the same problem, here's how I solved it:
In NVidia Control Panel, on the left side there is a section called "Adjust Desktop Size and Position". Inside there should be a setting called "Perform scaling on: ...", which was set to "Display" in my case. After setting it to GPU and running the game in fullscreen it now properly scales to full height.

Now I only wish I could preserve the sharpness of the image. Perhaps there's a setting for that somewhere too...
EDIT: The term I was looking for is "Integer Scaling", and it seems neither NVidia nor AMD support it right now, so I'm out of luck here. 

If someone has a graphic card, or monitor connected to it in the way it does not support upscaling, there are some 3rd party apps, that can be used. When I first needed that, it took me a long time until I have found some software, so I'll better give an example: OnTopReplica

OnTopReplica

This seems useless not ideal for this task? In fullscreen mode, the game being replicated won't detect keypresses while the replica is active. And it doesn't even have options for integer scaling.