[nwellnhof]

You can do amazing things with only a single SID channel. One of the most impressive examples is the in-game music of Hawkeye [1] which allows to use the remaining two channels for sound effects.

[1] https://youtu.be/es-rWnVSJ1c

[simonw]

That was incredible.

[selcuka]

That was made by Jeroen Tel, one of the wizards of the C64 music scene. See this for another example of a technical feat with the SID chip:

https://www.youtube.com/watch?v=qYnwR16NbPE