The Strange Zone or Stage X: The Strange Zone are a series of bonus levels introduced in Splatterhouse 3.
There are two types of "Strange Zone" levels: Cave and Garden.
On every level but Stage 5 & 6, it's guaranteed that you will play Stage X right after you finished the Stage you were playing. The requirement of this is completing the level before time reaches 2 minutes, otherwise you will play the next level. Doing this will take you to the "Garden" Strange Zone which are short and linear levels with weak-leveled monsters and no Bosses, there are also tons of 1ups in the way, which actually come handy in the actual levels. There are a total of 4 different Garden levels.
The "Cave" Strange Zones are much bigger and special, but at the same time harder to access than the "Garden" zones. These ones can only be accessed from either Stage 1 or Stage 2, there's no way to play both in a same playthrough. The requirement is completing the level before time reaches 3 minutes, otherwise you will either play the "Garden" Strange Zone or not play any of them at all but the next level. The Cave levels are special because the reward for beating them is skip one floor, thus, Stage 1 goes immediately to Stage 3 and Stage 2 goes to Stage 4 if done correctly.
The Cave levels are a series of labyrinths filled with strong monsters only, the map option is disabled so playing these levels might result EXTREMELY confusing coupled to the fact that the "bosses" are regular monsters too. The game also tends to switch monsters in case you re-enter a previous room to add more confusion. But on the good side, the game shows mercy and disables the Time as well. There are just 2 Cave levels.
Strange Zone: Caves Edit
A complete guide showcasing the maps and beasts from each level 
Strange Zone: Gardens Edit
- The Garden actually appears in the main game as a large corridor from Stage 5.
- For some reason, if Jennifer dies in Stage 1, there's no way to access any of the Strange Zones from Stage 2, no matter how fast you finish the level.
- In the US version, when defeating all the enemies from the Stage X (Stage 4), there's no Stage Clear music, rather, it lefts the level's music and fades into a cutscene. This bug was absent in the JAP version.