I'm still making it.
Fullscreen mode is added.I guess nobody will argue with statement that fullscreen mode is good. You can play the game without seeing window controls, distracting taskbar, have advantage of your big screen, immerse deeper in the upshot. The devil is in realization.
I guess many people like HOMM3. If you launch it now, the game will stick to it's own maximum size and then get ported to display's actual size. Interpolation will surely kill all crispy pixelart, smudge thin lines and distort fine fonts. Big display won't give you any advantage. The gaming filed will only blow up but you will see as much of it as you could see before fullscreening. Large field is what is expected, large buttons are less wanted with such a game.
That's why there's a special version of HOMM3 made buy kind people, which will launch expanded but not stretched, with a field as huge as your display is. Yeah, it has small buttons, rather small city screen, but it's the best you can have with a compiled game.
It would be different nowdays. Graphics are now drawn in vector, or in huge rasters which get downsampled on the fly, or in 3d-models being rendered in size you need, or all methods at once. Nowdays games adapt display size.
I am slowpoke. I've been making my game since 1024x768 was a common resolution. I had comics with proportions and size of my characters already set up, and my levels and my window got sticked to it. While it seem to be vector-ish (and it is by it's nature), it's really all resterized. Three sizes for characters? Three sets of sprites. I could shrink one big set, but it would get my edges oversharpened. I had no clue how to fix this and I'm not sure I can do it now. The only expirience I have is Johnatan's Blow one with fixing fading trees in upcoming "The Witness" (which were remade since then) —
http://the-witness.net/news/2010/09/computing-alpha-mipmaps/.
What could I do then with fullscreen?
I made up the solution quite ago, but only now have done it.
Small rooms get centered in black field. It sounds easy, but it required one more refactoring.
Build 0.0.7.3:
https://yadi.sk/d/yjS331bumaYpa