Sure, drop me an E-mail. (Feel free to write in Hungarian... ;))

I've put online the EXE only at http://sta.c64.org/shared/MGPRS2.RAR . Anyone can point me to a software that finds out what EXE compressor/encrpytor has been used on it and/or a software that can unpack it? I've never been very successful with unpacking EXE's manually, even in the DOS era... :o

I would recommend Quick Unpack - handles UPX, ASPack, PE Diminisher, PECompact, PE-PACK, PackMan, WinUPack and more
a load of other specific unpackers can be found here:
EDIT: FileDETECT detects a linker inside the EXE as Watcom WLink

Thanks but, it seems, none of those support the encryption utilized on this EXE... :(

yep, me too - it looks like a custom one :(