Every texture of The Settlers: Heritage of Kings reworked in high resolution with The Witcher 3's own surfaces and art from your copy.
Play The Settlers: Heritage of Kings – History Edition as always, but in the world of The Witcher 3, and in much higher resolution.
When you press Play, Witcher Siedler reads textures and artwork from your own Witcher 3 installation and reworks Settlers' graphics with them. No game files are shipped.
What changes: every texture except the font glyphs
Campaign, free maps and both expansions play as usual.
Needs: both games installed. The loading screens use The Witcher 3's bonus artwork folders. The first Play takes about two minutes to rework the textures.
Undo: run Restore-Siedler.cmd in %LOCALAPPDATA%\WitcherSiedler, or verify the Settlers files in Steam.