The ground graphics look blurry and indistinct

[LC-Zorg]

Maybe their appearance is a matter of sentiment, because these graphics are closer to the original, but I don't feel it and for me it simply looks worse than in OpenGFX1. The impression is somewhat similar to OpenTTD in the browser version, where the graphics are enlarged by default x1.25 (at least in my case) and are also blurry. It seems to me that this is a matter of too wide grid lines. On the slopes, where they are much less distinct and thinner, this blur effect is not there. Also, turning off the grid makes this effect disappear.

I did a small test for the subarctic climate - mainly the thinned lower left edge

[PeterN]

If anything, the only blurriness I see here is in the OpenGFX1 tiles. If you've got something scaling to 1.25x then any blurriness introduced by that is nothing to do with the baseset.

[zephyris]

I have the original OpenGFX1 sources. They use a 1px wide border, pure black, overlayed with 45/255 opacity in normal mode, using Paint.NET. However, they did get manually tweaked over time. OpenGFX2 uses a 1px wide border, pure black, overlayed with 40/255 opacity in normal mode, using Python/Pillow. So, from pure numbers, the gridlines are almost identical. Is there anything else you can add to describe more clearly?

edit One thing I have noticed, is that original TTD graphics for arctic and tropical climates use a '0.5px' border. This is something I'd be interested in testing, so I'll leave this open for now.

vs.

[LC-Zorg]

Well, even if technically they are the same thickness, in the game it definitely doesn't look the same.

Here mainly the bottom right / top left line is clearly thicker.
It seems to me that this disproportion in thickness may also contribute to this effect.
If you have drunk too much alcohol or not had enough sleep, what you see also blurs - in the direction of the change of the focus point. When you blur the image of the grid in this way, the lines going in the direction of the change of point will be thinner than the perpendicular ones. Here you get this blur effect without alcohol. ;)