6502.org

In 1983, Rescue on Fractalus and Ballblazer, the first releases from Lucasfilm Games, were built with a system written in Lisp. It was a 6502 assembler with Lisp syntax and a Lisp-style macro facility, written in Portable Standard Lisp, running in Berkeley Unix on a 4MB VAX 11/750. Unfortunately it was eventually abandoned because the developer had left and it was a bit of a strain on the VAX that was shared by the whole development team.

...
See also The Influence of the UNIX® 1 Operating System on the Development of Two Video Games(pdf) by Peter S. Langston

I wrote the programming tools, such as Macross, the universe’s second most powerful 6502 macro assembler - long story - that were used for essentially every 6502-based title we did.

The cross assembler and its macro library were written in Lisp. The Atari end of the download programs and the drum machine program were written in our Lisplike cross assembler. The rest of the tool software was written in C.

Lisp was chosen for the cross assembler because it only took two weeks to implement a cross assembler that allowed both assembler macro definitions and arbitrary Lisp expressions to be included in the assembly task. This allowed us to extend or reconfigure the assembler as we discovered unforeseen needs and deficiencies.

The macro library had two important effects. First, it allowed us to write in a pseudo-structured assembler that included ‘‘if-then-else’’, ‘‘for’’, ‘‘while’’, and other familiar constructs. Second, it acted as a first step toward a subroutine library of commonly used routines. We found that many of the routines we included in the initial set never were used at all, while others that we added as we went along were used frequently.
The download programs made it easy to maintain the source on larger machines running UNIX where we could assemble the code and debug syntactic problems using many different tools before sending executables to the small Atari machines for debugging. Unfortunately, debugging on the Atari was not always convenient, so we designed a dual-ported memory card that would allow us to debug the running Atari program using software running on the larger machines. We discarded the idea of simulating the Atari on the larger machines after discovering an incredible number of important undocumented eccentricities in the Atari hardware.