Aside from BASIC and 8080/Z80, FORTRAN.
FORTRAN was -- for some still is-- the 'Perl' of scientific computing. Get it in and get it done... and it doesn't always compile down very tight, but always fast because for mainframe developers getting this language optimized for a new architecture was first priority.
FORTRAN IV and Dartmouth BASIC (I'll toss in RPG II also) were the 'flat' GOTO-based languages, an era of explicit rather than implicit nesting -- a time in which high level functions were available to use or define but humans needed to plan and implement the actual structure in programs mentally by using conditional statements and labels to JUMP over blocks of code. Sort of "assembly language with benefits".
Crowther's PDP-11 Adventure version was running on the 36-bit GE-600 mainframes of GEISCO (General Electric Information Services) Mark III Foreground timesharing system... this is in the golden age of timesharing and no one did it better than GE. It took HOURS at 300bps and two rolls of thermal paper to print out the source and data files, and I the Adventure code and data out on the floor and traced the program mentally, keeping a notebook of what was stored in what variable... I had far more fun doing this than playing the game itself.
Then the "real life" adventure began. I started poking around on the Mark III timesharing system, and found a way to jump out of my partitioned access and explore. What really helped was a collection of FORTRAN/77 system utilities written by an engineer working at GEISCO (this is General Electric, no relation to GEICO and the year is ~1980). Their development environment as well as the commercial systems were controlled by password protected accounts, each with file/user areas... BUT there was also this command line debugger that was able to write to memory regions beyond your own job, and if you were able to parse out memory structures (reading source for the utilities helped) you could "punch yourself in" to any user number (location), effectively changing identity to that of another user and seeing their files. Or examine the buffers containing character streams of other users' terminals in real time. It was fascinating and I soon had developed a suite of tools in F77 to assist in exploration of the system, leap-frogging onto the commercial file systems too. I kept the source encrypted by the F77 'SCRAM' function, decrypting it only to edit and compile. My cache of tools was stored "in" a user number that did not exist, you can think of it as a unpointed-to lost cluster of sorts. I was totally white hat about it, never prying into customer files (McDonald's etc.) and even wrote a summary of vulnerabilities and dropped it into one of their secure areas. I just wanted to be hired. Cat 'n mouse games ensued, even a trace and FBI phone tap. GEISCO originally thought I was a rogue employee but when they learned I was just a kid the heat was off, they were afraid of public embarrassment. They bought me a plane ticket to Rockville MD so they could pick my brain, and the matter was closed soon after. I was not hired.
Lots of people have played Colossal Cave Adventure over the years, but in my mind the game is synonymous with the Mark III timesharing system itself, that was the biggest cave of all.
I had write access to their entire network. What did I do with my "superpower"? Well for one thing, I scanned to find ALL copies of Colossal Cave Adventure on their system, there were about a dozen that had been copied by various engineers. In each one I patched the text file to add a line to the description of the Orange Stone Room:
You are in a splendid chamber thirty feet high. The walls are frozen rivers of orange stone.
A recently carved inscription on the South wall reads, "ARTOO DETOO WAS HERE."