I ended up at the art section of the Interactive Fiction Archive
and I was curious as to the format of the
I downloaded one and much to my surprise,
it was an IFF file.
I haven't encountered an IFF file in the wild in over twenty years.
So it seems that a
.blb is a blorb file,
used to save resources for an interactive fiction game.
Going further down the rabbit hole,
it seems that compiled Erlang code is also stored as an IFF file,
although it's a slightly modified version
(Erlang uses 32-bit alignment while the IFF standand only mandates 16-bit alignment,
which makes sense given IFF was defined in the mid-80s by Electronic Arts).
It's a bit of a shame that it wasn't used more often as it's not a bad file format, nor is it that complicated—the standard is less than 20 pages long, and a “parser” is about a page of code in any modern language today. But alas, the format never really caught on outside the Amiga community and it's hard to say why. Jerry Morrison, one of the creators of the format, lists maybe three reasons why in a retrospective but it's hard to say if those were the sole reasons, or if there were more. About the only modern format today that is somewhat based on IFF is the PNG format (it was probably more inspired by the IFF format, but it's not compatible with it).
Anyway, what a pleasant surprise.