Cheat mode:
Hold [Shift] and type one of the following codes:

Result - Code:

Invincibility - invunerability
Protect farm from jumping cows - oldmacdonald
Racing in the moon - flymetothemoon
All cheats active - haveall
Cows selectable as ships in arcade and multi-player modes - superdaisy
One shot kills - easyshoot
Unlimited smart bombs - supershoot
Unlimited lives - infinitelives
Unlimited weapons - infiniteweapons
Extra tanks - tanksalot
Low gravity - catwalk
High gravity - fatwalk
Normal gravity - iweighnormal
Toggle textures - masteroftheuniverse
Enable in-game cheat keys - cheatkey
Big ships1 - eroser
Wire frame graphics - wirewewaiting
Point graphics whatsthepoint
Disable shading- - flatbroke
Solid shading - solidasarock
Gouraud shading - gouraud

Cheat mode (command line):
Start the game with one of the following command line parameters:

Result: Command line parameter

View frame rate: -framerate
Select screen resolution: -screenmode
Disable lens flare effects: -nolensflare
Disable fog: -nofog
Disable sky: -nosky
Disable MIP mapping: -nomipmap
Disable surround sound: -no3dsound
Disable shadows: -noshadows
Disable network support: -nonetwork

In-game cheat keys:
Press one of the following keys after using the cheatkey code:

Result - Key:

Easy shots - [F2]
Invincibility - [F3]
Unlimited lives - [F4]
Unlimited weapons - [F5]
Smart bomb - [F6]
Quit - [F7]
Save current game - [F8]
Reloads stored game - [F9]
Toggle frame wait - [F10]
Restart - [F11]