Distella is a disassembler specifically for the Atari 2600. Since its creation, it has been modified to disassemble Atari 7800 code as well. It creates source code that is usually recompilable without any human intervention. It examines the code and performs some basic tracing routines which allow it to accurately distinguish data from code.

https://github.com/johnkharvey/distella

Most of the popular games in the 2600's library have been disassembled and reverse engineered over the years.[1] As for Activision, they pretty much don't really care about a bunch of hobbyists tearing apart their 40+ year old piece of software.

[1] https://web.archive.org/web/20230404054728/http://www.bjars....