During game-play type 'DEBUGUP' and hold 'Shift' while pressing the selected button for the described code.
E - Toggles Enviromental Mapping
G - Toggles Gourad Mapping
P - Toggles Phong Mapping
S - Toggles slow Motion
F - Toggles Fog
C - Toggles Cloud Shadows
M - Toggles 3D Models
L - Toggles Fly Mode
T - Display Frame Rate