Mate!
This looks fantastic and thanx! Also nice to see some Spectrum-Games in the ATARI-Homebrew-universe. I like the colour schemes of the Spectrum, but never had one. ATARI and Spectrum 8-Bits truly have a "stylish" aspect to them and that is due to their colour palettes. A field where the C64 was terrible in.
However, I cannot run your final ROMs. I have an original 7800 in my studio (With no Harmony-card, just many original Cartridges), but love to play 7800-Games Home on my Nvidia Shield TVPro (Android-TV 11) running them on RetroArchPlus (Which uses the ProSystem as Emulator), which is tremendously nice for playing NES, SNES, MegaDrive, PS1 and other things with per-shader simulated Scanlines and PC-Controllers. It runs ALL original 7800-ROMs in the a78-format and many finished homebrews as Ninjish Guy, Knightguy, Slideboyinmazeland, Galaxian and Dragon´s Decent (Half of the homebrews don´t work with RetroArch, I still don´t know why). Yesterday I tried to import and play the final versions of RobotsRumble and A.R.T.I. (That H.E.R.O.-clone) but just a black screen was returned by RetroArch´s 7800 Emulator.
Do I miss something?