BIGCHEATER - God Mode
or
JUGGERNAUT
(Oddly, in some games it is BIGCHEATER, and in others it is JUGGERNAUT.
Try both.)
NOCLIP - No Clipping mode (walk through walls)
or
WRAITH
(Same as God mode: sometimes it is one or the other)
FLY- Flying mode
Usually BIGCHEATER, NOCLIP, and FLY are together.
Usually JUGGERNAUT and WRAITH are together.