[Simh] GDT in Dungeon

[Bob Supnik]

GDT dates from a very early version of the game, in fact, before the 
game was actually finished.  I realized early on that debugging an 
interactive program with the traditional PRINT statements was going to 
be very cumbersome, and that the interactive debug tools of the day 
(1978) had no semantic understanding of the program.  GDT was the 
answer.  It enabled me to track when things went wrong, and to simulate 
parts of the game that hadn't been implemented yet.

Originally, GDT was just a command like any other.  Once the game was 
released, players quickly realized that it offered a simple way to short 
circuit the game and to undo mistakes.  Lost something to the thief?  
Take it back.  Getting killed too often?  Turn on immortality mode.  So 
I implemented a variety of challenges to prevent players from entering 
GDT without making the mechanism too difficult for me to remember.  I 
think the INCANT mechanism might have been the final PDP-11 challenge.

When I did the VAX version, I abandoned all that and went back to GDT as 
universally enabled, under control of a run time flag, GDTFLG.  I think 
I intended to turn GDTFLG off before releasing the VAX version, so that 
it would be impossible to get into GDT without patching the binaries; 
but in fact the final VAX sources have GDTFLG=1.

/Bob