Ok, call me Mr Thick-as-a-whale-sandwhich, but I'm not getting anywhere here.
I've downloaded los.zip, and it opens up just fine, so I'm presuming that the archive is undamaged. As the text file says that it contains maps "LOSMAP01 - LOSMAP09 and LOSINV01", I'm trying to run it with the following command:
gzdoom -file los.zip -warp LOSMAP01
GZDoom reports that it has loaded los.zip, containing 3 lumps. However, it later fails with a fatal error, reporting that:
"Execution could not continue.
Could not find map MAP00"
However, if I try to run it with just:
gzdoom -file los.zip
GZDoom reports, again, that it has loaded los.zip, with 3 lumps, but a new game drops me straight into Doom2's Map01.
And, yes, I am using the r635 subversion of GZDoom 1.3.14.
There is, I must presume, something fundamental and obvious that I've missed, but I'm damned if I can work out what it is. Any help will be gratefully received.