I have the same issue on one of my Systems. guigfx.library can't be found, but not only with iGame but with eagleplayer + EMPYGUI24 too.
This system is a copy of another one where iGame and eagleplayer work but with a handfull of additional programs installed (patches; p96 etc etc). My guess is that guigfx is in conflict with one of those, but i couldn't figure out what exactly.
EDIT: Working for me now. renderlib v40 was the culprit. with renderlib v32 everything works again. It seems there are 2 different renderlib on aminet.
https://aminet.net/package/dev/misc/renderlib68k