Atomic Bomberman Cheat: Level Editor
At the main menu hold Ctrl and push E 6 times for three options: Make your Own Level, Edit a Level, and Quit.

Atomic Bomberman Cheat: Campaign Modes
At the Player Select Screen, Push the letter "C" five times. You will then get to chose one of three campaign modes.

Atomic Bomberman Unlockable: Hidden Pictures and Themes
Go to the data folder and open the sound folder. In it you should find hidden pictures of Kurt, one of the creators. In the theme folder you will find different themes for your PC.

Atomic Bomberman Hint: Custom Game/Messages
Open the Interplay directory and under data/res, find the file "valuset.res", open it with word pad, or a text program. With this file you can edit the game. For message changing, just open the Interplay folder and find the file "messages", again, open it with a text program. Note: Always make a back-up of your game when editing files.