Anti-Frustration Feature

4 vs. Satan:
*Anti-Paralyze-Items. They make the dungeon the heroes cross a child's play.
Alex in Princess Quest:
*NONE
The Stone of Power:
*NONE
The Three Kingdoms
*As the game would be unbeatable otherwise, you can buy items even somewhere mid-dungeon.
Dragondawn
*Advance: There are some items before you fight the first three bosses. Afterwards, however, you're forced to prepare yourself for later bosses.
Harter Knall
*NONE
Hero Story
*NONE
Kill the Demons
*NONE
Satan Saga
*NONE
Story of Hero:
*As with "The Three Kingdoms", there are enough items to counter the bosses short before you can fight them.
The Legend of Devils
*Advanced: On top of making both enemies and bosses stronger it has a teleport spell much sooner than the main game.
The Sidestory Duology:
*NONE
The Time Of Bloody Fear:
*NONE