I recently updated the MCL64 code to more fully supports the 6502/6510 undocumented opcodes which appear to be necessary to run a number of the popular Commodore 64 games. 

It is interesting that some of them use unstable opcodes which yield inconsistent results yet can reduce code-side and speed by 30% or more! Clever programmers!

The code had been updated on GitHub: https://github.com/MicroCoreLabs/Projects/tree/master/MCL64/SourceCode

I took a few pictures using the MCL64 as the CPU in my Commodore 64: