My teory is if the Y/N are in a loop(the most probably).The best is search access to the ppi acess debugging in winape. Then folow the path to the calls or jumps That activate Y/N.
Maybe the best aproach is force a "n" or maybe forze the call or jump to the "N" path ignoring the Y part.
You need the winape,the z80 opcode manual, the cpcwiki detalis of access to the ppi.the I/0 table of acces in grimware.The notepad, and a lot of pacience.

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With this metod i dissasemble the super sweek until beginning. Only to discover I miss that idiot had .Because i searh modify the levels. And the version disc have a editor levels integrated.
We're going to do, I 'm from 464(without level editor). . anyway was googd experience to learn how cpc works.
For example examining a litte the final matrix trainer The game is in a loop between. 1CDB and 1CDE. When you press Y/n He exit the lop and continue to 1CE0(RET) and exit the call. from here is search the path in the two directions to know where is the bifurcation of Y or n in the code.