Gauntlet

In-game reset:
Press Select + Start + A + B.

Double supplies:
Begin a game in two player mode and intentionally allow player two to die. Move player one over the icon that represents player two's supplies to collect them.

Escape stun square:
Press Start to pause the game. Resume game play and jump off the square to avoid damage.

Continue game play:
Begin game play in two-player mode. Quickly press Start when losing a life, while the other player still is playing to rejoin the game with another character.

Hint: Clue rooms:
Clues can be found in rooms 16, 26, 46, 54, 66, 70, 81, and 90. To pass Merlin, collect all of them.

Hint: No damage from ghosts:
Shoot at a ghost and keep the button held. If timed correctly, the ghost will pass through your character without doing any damage.

Hint: Level 1: Secret exit:
Before you complete the level, return to the room that was entered through the first door. There will be a series of blocks here. The wall to the very right will have a block. It is the one that is two body lengths from the top wall. Attack the wall sticking out, and a new exit will appear, taking you directly to level 5. Is recommended that you get all the items before walking through this secret exit.
Information in this section was contributed by Talalis Darkshine.

Hint: Level 5: Secret exit:
In level 5, venture down and around toward the room that has the treasure chests in the form of EH. There will be a diagonal row of two blocks off the extension on the wall at the top of the screen. One body length away, there is a double set of blocks next to one another. Attack the one on the right to open an exit to level 9. Use it quickly, because it opens a path for monsters to reach you from the other side.
Information in this section was contributed by Talalis Darkshine.

Hint: Level 14: Secret exit:
On level 14, there are two exits. One is behind a door and the other is in a room with three acid puddles. The one behind the door looks like it is harder to get to. Thus, it is better because it has an army of ghosts in front of it. However, take the one with the acid puddles. It takes you directly to level 17.
Information in this section was contributed by Talalis Darkshine.

Hint: Level 98: Secret exit:
When you reach level 98, you will find a number of treasure chests. Only one contains an exit. If you happen to find that one before you die, you will not go on to 99 or 100 unless you have all the clues to the Orb.
Information in this section was contributed by randy.

Note: Use XRTW98Y7 as a password for the final room, if any of the Room 79 passwords are used.