[pavlov]

Anything with realtime graphics was probably written in assembly. There were game companies whose entire business was porting games between platforms, essentially rewriting the code for each machine.

Slower-moving adventure and RPG games might be in a higher-level language. (IIRC the original Wizardry was written in a VM-based Pascal for Apple II?)

Companies that specialized in adventure games would have their own interpreter and VM — Infocom's ZIL, Sierra's AGI, Lucasfilm's SCUMM. Game developers would write code in a scripting language against that company-standard VM.

Amateur games might be written in BASIC because every computer under the sun shipped with a BASIC interpreter back then.

C wasn't a practical option because decent compilers didn't exist for most non-Unix systems until the end of the 1980s — or if they did, they'd cost an arm and a leg. (I think the retail price for Microsoft's C compiler for DOS was several thousand dollars.)