Agree a manual really helps mastering the game.
Contacted the support about it, was told all manuals they could find were lacking quality to release it. From what I have seen on the web I can agree, often missing pages or manuals from another system, etc.
Got the game on CD-ROM from a German Green Pepper release, though there would've been enough space to offer manuals in all languages (as the game offers several languages) there's just the German on it. Been thinking about translating my PDF to English. Found the English original text in a file. Sadly the person who typed it didn't care about spelling, grammar or even periods. So I have to fix that myself.
Since I am fluent in both languages and not too bored to start such a task it'll take a while. Not as long as Duke Nukem Forever though. In my old job had Acrobat Pro, simplifies the work. Right now working my way through it with free tools from time to time.
My idea was if an English Green Pepper release of the game existed to get that manual would be great. But haven't even found any info about it. Green Pepper doesn't offer info about anything dated before 2000.
If anybody is interested in at least the German PDF manual let me know, it's small. Text is perfectly legible, the pictures in the manual are not very sharp but not needed anyway.