It's dangerous to go alone! Take this.

I'm programming games on the C64 and Vic 20 with machine code. More accurately with an assembler which makes it much easier. Games written in machine code run faster than those written in BASIC and you can take full advantage of what the Commodore 64 and Vic 20 can do.

It is not as hard to get started as you may think and you can even do all your development on a PC. There is a lot of support out there from the community, tools, videos and books.

Recommended development tools are C64Studio, CBM PRG Studio and my favourite Turbo Rascal. (The source code for Vic Nibbler is included with Turbo Rascal)