Warning: This page is a major gameplay spoiler. Read with care.
Parallel worlds (also known as West/East worlds) are worlds which can be accessed by digging through the giant rock walls at the edges of the world. They have a nearly identical world layout as the starting world, but are missing certain key structures such as the Lava Lake and the Giant Tree. They also have new wands, max health upgrade pickups, and perks. Any biome visited in a parallel world will have 'East' or 'West' prepended to their name accordingly (e.g. 'West Holy Mountain', 'East Desert'). Amusingly, this is true even of biomes with 'The' in their name, such as 'West The Vault'. Only one prefix will be added, regardless of how many worlds over the player is.
Entering a portal while in a Parallel World will send you back to the starting world, so it is generally required to dig into the Holy Mountain in order to avoid ceiling collapse. This quirk however means that it is very easy to return to the starting world.
Reaching a Parallel World
To reach a parallel world, you will need a good digging wand with powerful spells like Black Hole or Ground To Sand. Not only will you need to dig through a giant wall made of Extremely Dense Rock(which is roughly the width of the Lake), but unlike most, it has a part made entirely of a deadly material known as Cursed Rock. Crossing the section in its core will cause heavy damage to you while within the area.
For the damage issue, there are a few approaches to tackle it. You can:
- Constantly heal yourself with some sprayed bottled Lively Concoction.
- Block the damage entirely with Ambrosia. Combine with teleport for best results, as normal movement dissolves it quickly.
- Polymorph into a Jättimato or a Helvetinmato using chaotic polymorphine and tunnel through the dangerous section in one go. It might take a few tries to get the correct form and being as safely close to the Cursed Rock as possible is recommended. The normal Mato and the Pikkumato don't have the speed or the health to cross the gap without dying.
- Dig through the whole section first, then use Teleport Spell to quickly hop through it.
Each method has its merits.
Digging through the wall
To dig through the wall, the fastest method is to bring a wand with Speed Up or Light Shot, and at least 6 black holes (possibly doable with at least 4). If you don't have any speed modifiers then you may need more than 10 or 12 black holes to pierce the whole wall (a wand with Black Hole as an Always Cast is a godsend for this). The Projectile Repulsion Shield perk can significantly increase the velocity of Black Hole, but can introduce some terrible inaccuracy. This issue can be fixed with Horizontal Path.
Alternatively or in addition, a high–mana charge speed wand with Quadruple Scatter Spell Luminous Drill and Chainsaws can allow for a player to make slow but steady digging process through the wall. One can end up on the other side of the wall using a wand with ~150 mana charge speed with this method in under 20 minutes if they are skilled at digging. The benefit of this method is that it doesn't require any limited-use spells.
Differences to the Starting World
Many generated structures cannot be found in parallel worlds. This includes the Giant Tree, some Orb Rooms, the Dark Cave, and the Lava Lake. However, some exist, such as the Floating Island or the Pyramid. Where structures are missing, they will be replaced with a completely empty block, and the terrain around it may therefore look unusual or not connect properly. This is most clearly seen where the Lava Lake would be, at the connection to the adjacent shaft.
The Orbs of True Knowledge in parallel worlds are red instead of the usual color, and are instead known as the Orbs of Corrupted Knowledge. These orbs function as normal except that when picked up, they will cause the player to take damage over time equal to 44% percent of their max health. Like toxic sludge, it seems that the player cannot die from this damage. As usual, you can block this damage with ambrosia. Instead of containing certain spells the first time they are found, these orbs always contain a max health upgrade.
It should also be noted that each orb picked up adds to the orb counter in the top right as usual, further increasing the health of the final boss in the starting world (if still alive). There is also a particular secret ending (please add link/page) that requires more orbs picked up than are available in the starting world.
Issues and Crashes
Visiting too many PWs in one game may cause the game to struggle due to the sheer size of the save. Eventually, the game may crash due to memory overload. Therefore, a less resource-intensive, safer alternative to going to parallel worlds is to start a new game, and port the old 'player.salaseki' file to the new game to retain your perks, health and items, though some players may consider this cheating. Remember that the player's position will be the same in the new world as the old game, so you may get stuck in a wall if this is done while you are underneath the surface—and you will be in a parallel world in the new game if you ported it from an old one while the player was in a PW.