What are .STU files in the STampede disks?

[Foebane]

I am trying to extract the intros from these disk-based magazine issues:

 

ftp://fujiology.untergrund.net/users/ltk_tscc/fujiology/MAGS/STAMPEDE/

 

but while some are .PRG files which are easy enough to extract and run, some are this obscure file format called .STU that I cannot figure out how to use or convert easily.

 

Anyone know of what these are and how they can be converted?

 

[Foebane]

Problem solved, I simply renamed the .STU files to .PRG files.