The core Algol 68 language is indeed set in stone. But we are carefully adding many GNU extensions to the language, as was explicitly allowed by the Revised Report: [RR page 52] "[...] a superlanguage of ALGOL 68 might…
I would recommend the Informal Introduction to Algol 68, available in PDF at https://algol68-lang.org/resources
You can find some modern Algol 68 code, using the modern stropping which is the default in GCC, at https://git.sr.ht/~jemarch/godcc Godcc is a command-line interface for Compiler Explorer written in Algol 68.
The core Algol 68 language is indeed set in stone. But we are carefully adding many GNU extensions to the language, as was explicitly allowed by the Revised Report: [RR page 52] "[...] a superlanguage of ALGOL 68 might…
I would recommend the Informal Introduction to Algol 68, available in PDF at https://algol68-lang.org/resources
You can find some modern Algol 68 code, using the modern stropping which is the default in GCC, at https://git.sr.ht/~jemarch/godcc Godcc is a command-line interface for Compiler Explorer written in Algol 68.