Borderless window tools like ShiftWindow could do it if the Window allows to be resized. It won't be real fullscreen of course, but borderless fullscreen.

Without a game name, giving specific instructions is hopeless.

I could have told the name (mouja) but it's not what I'd call a mainstream game 🤣
Shiftwindow works but it only maximizes window frame, content is still a portion of screen (windowed). Same with another tool called ResizeEnable.

Myloch wrote:

Shiftwindow works but it only maximizes window frame, content is still a portion of screen (windowed).

Can you reduce the screen resolution to the same size as the "portion of screen" ?

Being a true Win3.1 title, I suspect it natively runs @640x480 256colors (or lower). It doesn't care about desktop number of colors and luckily I've been able to force 640x480 thanks to catalyst control center (lower res. available in XP control panel > monitor is 800x600 though). It's not true fullscreen and menu bar on top is visible but it's now similar to what I used to do in Win3.1

Myloch wrote:

Being a true Win3.1 title, I suspect it natively runs @640x480 256colors (or lower).

Hey, that's right! 256 colours should yield best performance and compatibility, as it allows palette cycling.
At least in real Windows 3.x. Some popular fractal programs also supported this (WinFract, etc).
Windows 3.1 reserves about ~20 socalled "static" colours for its own purpose,
hence some some games from that era don't use the full amount of colours for their own (or do they?).
If your'e going to convert some pictures for displaying on Win 3.1 (wallpapers, etc),
it may helps to convert them to 216 colours. XNView and IrfanView can do that. 😀

The Microsoft Windows Palette Manager
http://www.compuphase.com/palette.htm

The only WinG fullscreen Win3.1 (win32s) game I can think of is Fury3, which can set the display to 320x200x256

Myloch wrote:

I could have told the name (mouja) but it's not what I'd call a mainstream game 🤣
Shiftwindow works but it only maximizes window frame, content is still a portion of screen (windowed). Same with another tool called ResizeEnable.

Don't use the automatic function, ShiftWindow allows you to manually set coordinates, even negative ones (IIRC). Use that, place the window so the titlebar is off-screen. Assuming the game does not object to part of its window being off-screen.

I'm a potato at programming and I'm not expert about win3.1 games (and WinG). Do you think that real fullscreen is out of question?
I'm thinking that probably even something like dxgl or dgvoodoo2 can't do this.

Myloch wrote:

I'm a potato at programming and I'm not expert about win3.1 games (and WinG). Do you think that real fullscreen is out of question?
I'm thinking that probably even something like dxgl or dgvoodoo2 can't do this.

Obvious question: why do you need a real fullscreen?

Most Win 3.1 titles crash when you try to enter fullscreen mode on WinXP and above (when they have that option). Nitemare 3D also behaves the same and uses WinG as well.

filipetolhuizen wrote:

Most Win 3.1 titles crash when you try to enter fullscreen mode on WinXP and above (when they have that option). Nitemare 3D also behaves the same and uses WinG as well.

But the method I suggested works around that. It's not real fullscreen, but when the game fills the entire screen what do you want real fullscreen for?

It works and it's a good workaround I presume.
I've grabbed some nice clips, it will be online on my yt channel soon.
Thanks Zell.

ZellSF wrote:

filipetolhuizen wrote:

Most Win 3.1 titles crash when you try to enter fullscreen mode on WinXP and above (when they have that option). Nitemare 3D also behaves the same and uses WinG as well.

But the method I suggested works around that. It's not real fullscreen, but when the game fills the entire screen what do you want real fullscreen for?

I don't really mind running them in a window, but never found out what causes this crash. Fury3x even greys out fullscreen mode when it's not running on compatibility mode.