Turns out the palette is actually identical to that in wh40k.pcx

internal/data/palette.go

@@ -1,15 +1,12 @@
 package data
 
-import (
-	"image/color"
-)
+import "image/color"
 
 var (
-	// From Pic/wh40k.pcx. I didn't feel like implementing the read-in for this.
-	// Not yet, anyway.
-	// TODO: at least one of these colours is actually transparent.
+	Transparent = color.RGBA{R: 0, G: 0, B: 0, A: 0}
+
 	ColorPalette = color.Palette{
-		color.RGBA{R: 0, G: 0, B: 0, A: 255},
+		Transparent,
 		color.RGBA{R: 128, G: 0, B: 0, A: 255},
 		color.RGBA{R: 0, G: 128, B: 0, A: 255},
 		color.RGBA{R: 128, G: 128, B: 0, A: 255},