At the "Options" menu select "See Credits". During the credits screen, press U, L, D, R, U, R, D, L, and U. If done correctly, you'll hear a sound. You now have a new option added to your in-flight options menu called "Re-Supply" which will re-fill your items to max allowed when selected.
Put the game Thunderforce II into your Genesis, and go to the option screen. Choose level five of the training mission with five men. Pull the Thunderforce II cart out of your system without turning off the power, put in the Fantasia cartridge and hit reset. [WARNING! Perform this trick at your own risk. Switching carts with the power on can damage your system and/or your game.]
In a two-player game. At the option menu select "Control", then highlight the "Point" option. Press B and you'll find that you can set the point value to zero. Do this for both players, then challenge a friend to a two-player "Vs." battle. Your point globes will be replaced by five-digit counters that count how many rounds you've won without ever ending a battle.
At the options screen, choose the Weapon icon. Then discard the
weapon you are equipped with and Punch will be your active weapon. While it is undocumented, it is a very powerful weapon. If you change your mind, you can pick up your old weapon again.
Same Character Select:
In a two-player game, player one should hold (U+A) while choosing a character. Then player two can now choose the same character.
On controller two, hold START and press (A+B), then on controller one press START.
Walk Through Walls:
Walk up to a wall in any stage of the game. Turn away from the wall, then hold A and point the directional pad away from the wall. The instant you see Conrad start to run, quickly release the A button and point him back at the wall. He should be able to walk right through it. Although, if you walk through a wall with nothing behind it, you can die or crash the game.
When low on life, pause the game, and then resume with player two.