Occasionally GTW64 is passed on software which did in fact get a release, but a very limited one and which has not yet been preserved for others to enjoy.
Joe and the Serif is one such game, preserved by a contributor called Pudva, this is an interesting game released in Hungary (May need to know some Hungarian to play the game :) ), which also saw a release on the C16/+4
You can grab a copy of the game here.
A big thanks to Pudva for digging this out, and Puchala László for the name correction.
NOTE: This was originally published back in 2011.