Follow the given methods.
These codes are to be entered at the ''Press Start'' screen (the one with the neat picture of the SDF-1).
The indication that the code was entered correctly will be indicated by a chicken clucking (most likely in reference to the Lucky Chicken, not the courage of the player).
This is a neat code. By using this one, your weapon upgrades do not wear off. Instead, your primary weapon will change when you pick it up.
Note: The speadfire weapon now changes its firing patterns when you move forwards and backwards.
Note: Sometimes, the weapon upgrade pickups become glitchy and fuzzy when this cheat is in effect.
To use this cheat, enter your name as ''*SDF1***.'' This means that you can enter any name that contains ''SDF1'' as long as the fortress's name starts from the second spot. Essentially, your player's name needs to have ''SDF1'' in it starting from the second character. The one I used was ''ASDF1.'' Where the asterisks are located, you can enter any character.