Kick Assembler

Kick Assembler was written by Denmark's Mads Nielsen and released in 2006. It is built in Java, so it runs anywhere, but what sets it apart from older assemblers is the scripting layer: whole loops, math and algorithms can run while the code assembles and feed the result — sine tables, unpacked graphics, generated routines — straight into the finished binary.

That suits the demoscene perfectly, where half the art lies in precalculated data. Alongside older assemblers like ACME and 64tass it has become a standard tool for new C64 code. Still actively developed.