Programming Your Own Codes.

The codes listed in this e-book give you an idea of the kinds of effects you can create by programming your own codes. When trying your own codes, keep in mind the following guidelines:
 
  • The easiest way to program your own codes is to make slight changes to existing codes.
    • The next section shows you how to do this in more detail.
    • Remember if you are making small changes to existing codes, you must have 8 characters in the code.
  • You can also program codes by simply using random characters.
    • Remember that you must have 8 characters in the code.
    • Using 2 or more codes at a time is a much more difficult way to program random codes, since it's harder to tell which code is having an effect.
  • Some kinds of codes are easier to program than others.
    • The easiest ones are codes with numbers in them (for example, number of lives, number of bullets, number of weapons, number of seconds or minutes on a timer).
    • Some kinds of codes are harder to program, such as "Infinite Lives" or "Super Mega Power."
  • Many codes you create will have some effect, but often it will be such a small change that you may not notice any difference.
    • YOU MAY HAVE TO TRY MANY RANDOM CODES BEFORE YOU GET AN INTERESTING EFFECT.
    • If you find a random code that has an interesting effect, then try changing it by using the techniques shown in the next section. This way, you are more likely to "home in" on a really good effect.

Your success in code programming will depend a lot on luck. Keep trying! Of course, some of the effects you create you may not like. Almost any effect is possible - good, bad, interesting, annoying, fun, or just plain silly.

If a code you program interrupts the game or causes an undesired effect, just turn the power off and then on again, or deactivate the code(s) and press "reset" when using the Game Genie feature in an emulator.

Finding New Game Genie Codes.

The following programming methods work best when the code you wish to change has numbers in it, such as "Start with 10 weapons". It is much more difficult to alter or program codes like "Infinite Weapons".

The best way to proceed is to write down the original code, look up the choices in the tables below, and then write down all the variations underneath the original code. This way, you can return to your Game Genie with your own list of codes to try.

If a code you program interrupts the game or causes an undesired effect, just press reset or turn off the power and turn it on again or deactivate the code(s) and press "reset" when using the Game Genie feature in an emulator, and then program different codes to play.

Code Tables.

Find the letter you want to change in one of the tables below, then substitute it with one of the other letters from the same table. Read the examples below for more detailed explanations of when and how to use each table.

You may also wish to print these tables out for quick reference whilst reading the explanations or programming your own codes. You can find a copy of these tables suitable for printout by clicking here.
 

1

2

3

4

5

6

7

8

 Table 1

A

E

J

N

T

Y

2

6

 Table 2

B

F

K

P

V

Z

3

7

 Table 3

C

G

L

R

W

0

4

8

 Table 4

D

H

M

S

X

1

5

9

1

2

3

4

5

6

7

8

 Table A

A

B

C

D

E

F

G

H

 Table B

J

K

L

M

N

P

R

S

 Table C

T

V

W

X

Y

Z

0

1

 Table D

2

3

4

5

6

7

8

9

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

 Table X

A

C

E

G

J

L

N

R

T

W

Y

0

2

4

6

8

 Table Y

B

D

F

H

K

M

P

S

V

X

Z

1

3

5

7

9

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

 Table L

A

B

C

D

E

F

G

H

J

K

L

M

N

P

R

S

 Table R

T

V

W

X

Y

Z

0

1

2

3

4

5

6

7

8

9

Method #1.

Using this method, you change the sixth character of an existing code. Look up the sixth character of the code in tables 1 to 4 above, you can then replace it with any of the other characters from the same table.

Let's use an example to see how this works. A Game Genie code for Sonic the Hedgehog is SCRA-BJX0, this makes each ring you get count as 2. The sixth character of this code is J. You'll find this in table 1 as shown here.
 

 Table 1

A

E

J

N

T

Y

2

6

You can replace the J with any of the characters from Table 1 to try to get a different point score for the rings, so lets write all those down and see what happens:

 Code  Effect
 SCRA-BAX0  Each ring counts as 8  
 SCRA-BEX0  No Effect
 SCRA-BNX0    Each ring counts as 3
 SCRA-BTX0  Each ring counts as 4
 SCRA-BYX0  Each ring counts as 5
 SCRA-B2X0  Each ring counts as 6
 SCRA-B6X0  Each ring counts as 7

 
 

All these codes appear in the Sonic the Hedgehog
codes already, except the second code which has
no effect, but at least this gives you a clearer picture
of how Method #1 works.

Method #2.

Using this method, you change either the first character, the second character, or both the first and second character of an existing code.
 
  • The first character can be replaced by ANY other character in the Game Genie character set (A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S, T, V, W, X, Y, Z, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
  • The second character can only be replaced using characters from tables 1 to 4 above.

Try changing just the first character, then just the second. Then try changing them both at once. In general, replacing the first character will have a more dramatic effect than replacing the second character.

To see how this method works, let's look at another code for Sonic the Hedgehog, AY3T-AACL - Start with 5 lives.

Changing the first character:

A can be changed to any other character allowed in the Game Genie set (A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S, T, V, W, X, Y, Z, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Different characters were tried until E was found to make a change; the resulting code is EY3T-AACL - Start with 37 lives. (This code does not appear in the Sonic the Hedgehog codes.)

Changing the second character:

This works the same way as method #1, except you change the second character instead of the sixth. Using the same code from sonic the hedgehog, AY3T-AACL, using tables 1 to 4 again Y is found in table 1 and as with Method #1 can be changed to any other character from the same table.
 

 Table 1

A

E

J

N

T

Y

2

6

Again the letter was changed until the letter J gave the following code: AJ3T-AACL - Start with 2 lives. (Again this code does not appear in the Sonic the Hedgehog codes.)

Changing both the first and second character:

This is much more difficult task with a possible 256 combinations to try for each code. In the example from Sonic the hedgehog if the first letter A is changed to N, and the second letter Y is changed to N to give NN3T-AACL you will now start with 99 lives. (Again this code does not appear in the Sonic the Hedgehog codes.)

Method #3.

Using this method, you change the seventh character of an existing code. This will generally only have a small effect on how the code behaves. When changing the 7th character you can only use letters or numbers from tables A to D above.

As with the previous examples look which of the tables your code is from and substitute it with another letter from the same table, for example using the following code from Boogerman, HH2A-A2FN - Free boogers, the 7th character is F which comes from table A as shown here.
 

 Table A

A

B

C

D

E

F

G

H

The letter was changed until the letter H gave the following code: HH2A-A2HN - Boogers hardly travel at all, you must stand right next to your target to hit!

Method #4.

Using this method, you change the fifth character of an existing code. Making a change to the 5th character will rarely produce any results, although when it does it will generally give you a larger change in effect than Method #3, . When changing the fifth character you can only use letters and numbers from code tables X and Y.

As with the previous methods find the 5th character from your existing code in tables X and Y and try replacing it with another letter or number from the same table.

Method #5.

Using this method, you change the fourth character in an existing code. This will generally have a fairly large effect on the way a code behaves. You can change the 4th character in two different ways:

To make a medium change.

To make a medium change, using tables 1 to 4, replace the 4th character from your code with a character from the same table but four columns ahead of it. For example if the 4th character is G which is from Table3, you should replace it with 0 as shown here.

 

 

1

2

3

4

 

1

2

3

4

5

6

7

8

 Table 3

C

G

L

R

W

0

4

8

When the character to be changed appears in columns 5 to 8 you should simply "wrap around" the table ie count 4 columns going from column 8 to column 1. For example, using the following code from Boogerman: HH2T-A2FR - Free loogies. The 4th character is found in table 1 and counting 4 across gives us the letter A as shown below.

4

1

2

3

1

2

3

4

5

6

7

8

 Table 1

A

E

J

N

T

Y

2

6

This gives us the code HH2A-A2FR - Boogers disabled after shooting once.

To make a large change.

To make a larger change, find the 4th character from your code in tables L and R and try replacing it with one of the other letters or numbers from the same table. This will rarely produce any results so you may be better off trying a different method instead.

Some codes made using Method #5 are more likely to produce results than others. Most of the time the 4th character should be an A or T, other letters that you commonly see here are: B, C, D, V, W, and X. Other characters are generally not used for the 4th character, if they are it's usually best to try the "medium change" method when searching for new codes.

Method #6.

If you look at the 7th and 8th characters together you can treat them almost as a two digit number, and adding or subtracting "two" from this number by changing the 8th character in a code can be a very good way of fine tuning it.

For example, lets take an imaginary code of XXXX-XX4L, the characters we are interested in are the last two "4L" and we are going to change the last letter "L".

To change the 8th character look for the letter "L" on the Game Genie Code screen (shown on the right) then look for the letters or numbers which are two ahead and two behind it. So to move the code ahead by two you would change the "L" to a "N" to give the code XXXX-XX4N, and to move the code back by two you would change it to a "J" which would give the code XXXX-XX4J.

What happens if the 8th character is already as far as it will go? Let's use another imaginary code again: XXXX-XX48, to add "two" to this code you have to wrap around from 8 to A. Now remember even though we're only changing the 8th character that characters 7 and 8 work together like a number, if you "roll" over the top you have to add "one" to the 7th character as well. So taking our example the 8 would change to a A and because we've "rolled over" we also have to add "one" to the 7th character "4" by looking on the Game Genie Code screen and looking what the next letter or number is, which in this case is 5. So our new code would be XXXX-XX5A.

The same is true in reverse. What if you want to go back from XXXX-XX4A? To take two from A, you have to wrap back around to 8, what means that you have to subtract "one" from the 7th character. Again looking on the Game Genie Code screen change the 7th character for the letter or number before it, the result this time is XXXX-XX38.

Now what happens if both characters are at their highest or lowest values, XXXX-XX98 for example? From here, it turns into a horrid mess of binary mathematics so if you find yourself in this position it's best to switch to a different method of changing the code.

With this method, it sometimes helps to add or subtract "four" at a time, you may save yourself some time and frustration by moving along more quickly. If you "roll over" again you should still only add or subtract "one" from the 7th character though or you'll miss a whole group of codes. You can always switch back to changing the code "two" at a time to fine tune your code later. If you're wondering why we're adding or subtracting "two" instead of "one" from the 8th character it's because the eighth character can only be one of the letters or numbers from tables 1 and 3, adding "one" to it would give an invalid code (from tables 2 and 4).

Let's try an example. Using the code HH4A-A2AJ - Free super burps, from Boogerman, the 8th character was changed by 2 characters at a time until the letter L was found to have an effect. The resulting code HH4A-A2AL only allows Boogerman to super burp once, not very useful but at least you can see a change.

Method #7.

Another good way to alter an existing Game Genie Code is to change the 3rd character, this usually produces related effects in a different area of the game.

The 3rd character can be replaced by ANY other character from the Game Genie character set (A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S, T, V, W, X, Y, Z, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9).

For example using the following code from Shining Force:

GKJT-FEML - Hero starts with Max MP (50MP).

The 3rd character was altered until the letter K was found to have an effect. The resulting code GKKT-FEML affects Domingo's movement rate and agility.

Finding Random Codes.

You can also attempt to find new codes by simply entering random letters or numbers, whilst this method is fairly easy it is nearly impossible to find a specific code this way.

REMEMBER YOU MAY HAVE TO TRY MANY RANDOM CODES BEFORE YOU GET AN INTERESTING EFFECT!

However here are a few simple rules that you can follow which will hopefully improve your chances of success:
 

  • All Genesis/Mega-Drive Game Genie codes use 8 characters which can be selected from the list on the Game Genie code screen (A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S, T, V, W, X, Y, Z, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9).
  • Remember that the Letters "I" and "O" are NEVER used, if you see an "I" or an "O in a code it means the numbers ONE and ZERO! The letters "U" and "Q" are also never used.
  • The 2nd, 4th, 5th, 6th, 7th, and the 8th characters in a code all have restrictions as to which letters or numbers you can use:
    • for the 2nd character you can use any character from the Game Genie character set. However when changing an existing code you must replace the 2nd character with a letter or number from the same table (using tables 1 to 4 - see method#2).
    • for the 4th character you can use any character from the Game Genie character set, however some letters are more likely to be used than others, 95% of the time, you should use the letters "A", or "T". Other letters that you can use here are: B, C, D, V, W, and X. (see Method #5). Also when changing an existing code you must replace the 4th character with a letter or number from the same table (using tables 1 to 4 for a medium change, or tables L & R for a larger change - see method#5).
    • for the 5th character you can use any character from the Game Genie character set. However when changing an existing code you must replace the 5th character with a letter or number from the same table (using tables X & Y - see method #4)
    • for the 6th character you can use any character from the Game Genie character set. However when changing an existing code you must replace the 6th character with a letter or number from the same table (using tables 1 to 4 - see method#1).
    • for the 7th character you can use any character from the Game Genie character set. However when changing an existing code you must replace the 7th character with a letter or number from the same table (using tables A to D - see method#3).
    • for the 8th character you can only use the letters or numbers from code tables 1 and 3 (see method #6).

Make a note of the codes that you have tried, and what effect they have (if any), this will save you time later! Also when trying to find codes in this way it's much easier to just try one code at a time, using 2 or more codes at a time is a much more difficult way to program random codes, since it's harder to tell which code is having an effect.

Many codes you create will have some effect, but often it will be such a small change that you will not notice any difference. If you find a random code that has an interesting effect, then try changing it by using the techniques shown in Method #1 to Method #7 above, this way, you are more likely to "home in" on a really good effect.

Fixing Problem Codes.

If your code is crashing the game, there is a possibility that it represents a bad value. Certain parts of the game are restricted in the changes you can make to them, however all is not lost. Some codes alter parts of the game containing literal numbers, for example "Start with X of something", whilst others alter Genesis/Mega-Drive program instructions (two byte machine codes), for example "Infinite something". If your code happens to modify a program instruction then the replacement value must also represent a valid program instruction or the program will crash.

Many of the codes in this e-book contain the values you need, "Infinite something", "Invincibility", or even the "Master code" are good candidates to help you fix problem codes. "Start with X of something" codes are not, so try to avoid these and other codes with discrete numeric values. Ideally if you're looking for a "fix code" using the method described below you should first start by using another code from the same game. If no suitable codes are available for your game, or your code is still causing problems, you can try using codes from another game, although you may have to try codes from several different games before a fix is found.

Let's use some codes from Boogerman again to show you how to try and fix problem codes, for example the code GX2A-BEFA causes the game to freeze when you try to throw a booger. Looking at the other codes available for Boogerman a likely "fix code" was found, RY4T-A60W - Infinite lives.

Step 1.

Start by taking the first character from the good "fix code", RY4T-A60W, and putting it into your problem code. So with our example GX2A-BEFA becomes RX2A-BEFA.

Step 2.

Next we need to find the right character for the second character of your problem code, this can be any letter from Code Tables 1 to 4. To narrow this down to a likely valid value we can use the problem code and the good "fix code" and cross reference them on the tables. Find the 2nd character from your problem code on the table, in this case X, and mark that row across as shown below, then find the 2nd character from the good "fix code", Y, and mark it's column as shown. Now look where the row and column cross each other on the table as shown here, take the character where they cross, 1, and place it into your problem code to give  R12A-BEFA.
 

1

2

3

4

5

6

7

8

 Table 1

A

E

J

N

T

Y

2

6

 Table 2

B

F

K

P

V

Z

3

7

 Table 3

C

G

L

R

W

0

4

8

 Table 4

D

H

M

S

X

1

5

9

Step 3.

Next you need to find a good value for the 5th character in your problem code, this can be any character from tables X and Y. Look for the 5th characters from your problem code and the good "fix code" in these tables and see if they both come from the same table. If they do then you don't need to change the 5th character of your code, if not then change your 5th character to the character in the same cell on the other table.

So using our example codes, R12A-BEFA and RY4T-A60W, you can see that they appear in different tables as shown below so in this case we change the 5th character in our problem code to the character from the same cell on the other table, A. This gives us the new code R12A-AEFA. (It should be noted that in this example both the 5th characters happened to come from cell 1, this wont always be the case, if for example the 5th character from our problem code had been P then you would have replaced it with the letter N.)
 

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

 Table X

A

C

E

G

J

L

N

R

T

W

Y

0

2

4

6

8

 Table Y

B

D

F

H

K

M

P

S

V

X

Z

1

3

5

7

9

Step 4.

Next you need to adjust the sixth character which is a lot easier, as with the first character just copy the sixth character from the good "fix code" into your problem code. So using our example codes R12A-AEFA (problem code) and RY4T-A60W ("fix code") will give you R12A-A6FA.

Step 5.

Finally you need to alter the 7th character and for this we need to use tables A to D. As with the 2nd character find the 7th character from the codes in the tables and mark the row from your problem code, R12A-A6FA, and the column from the good "fix code", RY4T-A60W. Look at the character where the two cross, G as shown below, and replace the 7th character in your problem code with this character to give R12A-A6GA.
 

1

2

3

4

5

6

7

8

 Table A

A

B

C

D

E

F

G

H

 Table B

J

K

L

M

N

P

R

S

 Table C

T

V

W

X

Y

Z

0

1

 Table D

2

3

4

5

6

7

8

9

By using the data value of the good "fix code", RY4T-A60W, the problem code, GX2A-BEFA, has been transformed into R12A-A6GA. Trying this in the game causes boogers to drop straight down when Boogerman is standing still or jumping straight up, not very useful but the code is no longer causing the game to crash and you can use this new code as a jumping off point for finding new codes using methods 1 to 7 above.

This method isn't guaranteed to stop every problem code from crashing, it will only fix codes that crash the game because their values are invalid, but it's worth a try if you're stuck. Don't forget that if you don't have any suitable "Infinite Something" type codes for your game, or they don't "fix" your problem code, you can try using similar codes from other games although you may have to try codes from several games before a "fix" can be found. For example it was found that the problem code used in the above example could also be "fixed" using code 47 from Sonic and Knuckles.

Master Codes.

Some games require a "master code" to be entered before they will work with a Game Genie, if you have a master code for a game you MUST USE IT when trying to find new codes.

If your game crashes when trying to find new codes there is a way to tell if your code is a problem code or if the game requires a master code. Enter your code in the Game Genie Code screen as normal but before you press the start button to begin the game make sure that the effects switch is in the OFF (down) position, the effects light should not be lit.

Now press the start button and wait until you first see any sign of the game starting (usually about 5 seconds). Then immediately flip the Game Genie switch "ON" (up). If the game still crashes then it's likely that your code is causing the problem, try using the methods described in the "fixing problem codes" section above.

This works slightly differently when using the Game Genie function in an emulator as master codes are only required when the game is starting up, and as Game Genie codes are never active when you first load a game they are generally not required. The only time you will need master codes when using emulators is when you press the "reset" button, when you do this the code is still active and you will encounter a red screen if a master code is required. This can be fixed by either entering the master code, or switching off any active codes, and pressing "reset" again. Unfortunately this makes it a little difficult to tell when a game requires a master code but generally it's likely that the code you have entered is a problem code, especially if the game starts but then crashes at a later point in the game after you press "reset".