Full Health and Ammo:
At any point while playing, press M, I, L at the same time.
Debug Mode:
In the DOS promt type "sod" (or "spear") followed by a space and a
minus sign and type debugmode.
Eg: C:\SPEAR>spear -debugmode
Then when you are in the game hold Alt, Shift, and Backspace at the same time. A message will appear.....
And then use the following:
TAB + G - God mode TAB + B - Border colour TAB + I - Items and lots of points TAB + H - Hit yourself TAB + N - No Clipping TAB + E - End Level