As far as I'm concerned, the biggest issue I have with SCI development is the almost complete lack of proper sound resource tools. We need an all-inclusive SCI Sound Resource tool that can do everything SCI Viewer, Soundbox, SYX2PAT, BNK2PAT/PAT2BNK, and ADDWAV can do and more. Adlib emulation for proper previewing of sound resources via Adlib output would also be welcome. Currently SCI Viewer will only output to a MIDI device which obviously doesn't work well if you want to preview the sound in Adlib mode. An easier way to add loop points and cue points than how Soundbox handles it. Also, a built-in rudimentary MIDI sequencer would be nice to add quick fixes to MIDIs or even already converted sound resources.
I realise that would be a big job for anyone to take on and not everyone is a musician. But being a musician this is a major issue for me regarding creating SCI games. Especially since SCI centers around music with a lot more focus and attention than AGI ever did.
Besides that, if a VGA SCI IDE tool is ever completed it'd be nice to have a converter to convert back and forth between PCX/BMP/JPG/GIF/PNG/WHATEVER and background resources. I long to MOD SCI1+ backgrounds

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But I can't think of anything else for EGA games at the moment.