Codes
Onside kick, After scoring hold up+Turbo+Jump+Pass Extra blocker, While hiking the ball hold Turbo+jump+pass Hide play cursor, At the plays selection screen press up twice on the upper left play.

Various Cheats
Enter any of the following "Codes" at the Matchup screen: The numbers tell how many times press the TURBO, JUMP and PASS buttons.
For example, 5-2-5 means:
Press TURBO 5 times.
Press JUMP 2 times.
Press PASS 5 times.

Effect Code
Big Head Team 2-0-3 Right
Bullet Passes 2-5-0 Left
Fog On 0-3-0 Down
Headless Team 1-2-3 Right
Hide Name 1-0-2 Right
Huge Ball 0-5-0 Down
Huge Head 0-4-0 Up
Hyper Blitz 5-5-5 Up
Invisible 4-3-3 Up
Invisible Qb 3-4-2 Left
Late Hits 0-1-0 Up
More Speed 4-0-4 Left
Night Game 2-2-2 Right
No CPU Assistance 0-1-2 Down
No Fumbles 4-2-3 Down
No First Downs 2-1-0 Up
No Head 3-2-1 Left
No Interceptions 3-4-4 Up
No Out of Bounds 2-1-1 Left
No Punting 1-5-1 Up
Power Blockers 3-1-2 Left
Power Defense 4-2-1 Up
Power Offense 3-1-2 Up
Power Speed 4-0-4 Left
Power Teammates 2-3-3 Up
Random Players 1-1-5 Left
Show Field Goal Percentage 0-0-1 Down
Show More Field 0-2-1 Right
Smart CPU 3-1-4 Down
Thick Fog 0-4-1 Down
Tiny Players 3-1-0 Right
Tourney Mode 1-1-1 Down
Turn Off Stadium 5-0-0 Left
Unlimited Turbo 5-1-4 Up

Fat Players:
While playing pause the game and press Up, Up, Left, Left, Right, Right, Down, Down.

True Ending For Season Mode:
To obtain the true ending for season Mode you must beat Season Mode with a rating of 90.0 or higher

Secret Head Codes
After you have chosen arcade there comes up a screen with yes/no pick yes and put:
David-3456
Azpod-4777
Allen-7911
Gatson-1111
Brian-2221
Jove-6644
Bert-8735
Franz-8421
Byron-1969
JUan-6521
Franc-1221
Aubrey-6666