This is extremely cursed, but you are free to do things like this with a preprocessor:
#define programm program
#define abend end
#define keine_implizit implicit none
#define drucken print
programm pruefen
keine_implizit
drucken *, "hallo welt"
abend programm pruefen
Compile with gfortran -o pruefen pruefen.f90 -cpp