The game is exactly as on the Spectrum, even displaying graphical artifacts as Colour attributes and/or monochrome display for the game's window but not always the HUD, which may even often feature extra colours thanks to Raster colour changes, yet this doesn't really help to see what happens on the game's window. This just add insult to the shame !
Also sprites may display Transparency/translucency with background's colour(=colour clash), a typical Spectrum "feature".
Probably achieved by using almost the exact Spectrum code and emulating the Spectrum attributes on the CPC.