Changes

But sprites and animated stuffs are some sort of 1bpp Spectrum graphics (with attributes) transfered transferred into Mode0... probably with a CPU intensive process as the emulation (WinApe, option "find graphics"...) can't enable to find the graphics... (no pre-coded graphix). As a result we can seem ugly attributes and the Wide pixels of Mode0 can't do justice to the design of the varied aliens (on Speccy they manage to look quite good actually)

The use of the Hardwired Hard-wired sprites is obvious : the target/crosshaircross-hair... but sadly the bullets use most of the rest of the HardSprites slots while less or different method could have been used.

On emulator, the Colision Collision just seem to not work well, on real Hardware this must not be that different.. and the result must be laggy at best.

The playfield also use some raster technics which are quite similar to the Arcade... but halas sadly this simply diplays displays even more the unmasked tiles/characters from the sprites. could have been better provided the sprites were properly 4bpp coded as the "raster ink" would be used as a "sort of a mask".