Arrowheads are made of Psitanium, a rare psychoreactive mineral, and they are also the currency in the game. You can use Arrowheads to buy items at the camp store.
You can find these buried in the ground, and they'll also come out of destructible items in the environment. They'll let off pink shimmers on the ground. There's a lot of these, but they're kind of tedious to collect enough of to buy the good stuff. The Dowsing Rod item will help you gather them much more quickly.
Astral Projections are your lives. You'll get a few of them every time you enter a world and when you run out of Mental Health you'll lose a "layer of your astral projection," or in simple terms, a life. If you completely run out of astral projections you'll be sent back to the real world.
There are items within the stages that will replace layers, and also ones that will increase your max amount of layers. Be sure to collect these when you find them!
At a certain point in the game you'll start finding brains in jars. Finding brains is of course great for helping those that have lost them, but it will also increase your maximum Mental Health!
Inside of people's minds you'll find bright pink Cobwebs. Once you buy the Cobweb Duster you'll be able to clear these out. They're often blocking areas that contain items, but you can also turn them into PSI-Cards in Cruller's lab.
Late in the game you'll unlock the ability to use Confusion Grenades. These work similar to any grenade in a game, you toss them and the explode, causing enemies to be stunned.
Once unlocked, enemies will drop Confusion Grenades when they die just like how they drop mental health and raw energy.
Once you gain the Clairvoyance ability you might find a crow feather. You can hold onto these and use Clairvoyance to see from the perspective of the crow.
In each level there are 5 pieces of "Emotional Baggage" and Tags to match each one. You will have to find the tag first, and then the matching bag itself to release it. Each level will have a: Suitcase, Purse, Steamer Trunk, Dufflebag, and Hatbox.
The Dowsing Rod can be purchased from Cruller's Shop in the main lodge at the camp. It can be used to find deeper arrowheads than the surface ones, which have a much higher value than the surface ones.
To use it, equip it from your backpack and then walk around. Pay attention to the noise it makes and the way the controller vibrates. When you get right overtop of a deep arrowhead and all signals are going haywire, press 'Y' rapidly to pull it up. If you're pressing it like crazy and the meter isn't getting any more full then you aren't quite in the right spot (it's fussy.)
Figments can be found all over every level. They're fun little 2D neon sprites that are just randomly placed in each world. Collecting them is optional, but every 100 you collect will increase your pyschic rank.
If you are trying to collect them all then just make sure you explore every nook and cranny of every level. It also helps to look around at different angles because they can be hard to see sometimes, and some will be moving. You'll also need to have the Cobweb Duster to get to a lot of them.
After completing the Lungfishopolis level you'll be given this item. Using it from the beach will allow you to travel back and forth across the two islands in the game via the Lungfish.
Mental Health is what the game calls your health. It's represented by the brains meter in the UI. Destroying enemies and environment objects will release mental energy you can collect to restore your health. You can also consume Dream Fluff if you have it.
If your Mental Health is totally drained you'll lose a layer of your Astral Projection. If you lose them all, you'll be kicked out of the level and back to the real world.
Nets are obstacles in levels that allow you to bounce to reach certain areas. All you need to do is jump on them and you'll start bouncing, then hit the jump button with some good timing and you'll get a super high bounce off them. These are key for getting up to hard to reach areas.
These can be found around the campgrounds. They look like an eyeball (Psi-Core) with Psi-Cards circling around them. They're usually in tricky to reach areas. Collecting them will increase your Psychic Level.
You can also "build" these by collecting Psi-Cards, purchasing a Psi-Core, and going to the machine in Cruller's lab to assemble them.
More often than finding complete Psi-Cores you will find individual Psi-Cards. You can also convert cobwebs you collect into Psi-Cards in Cruller's lab. Every 9 Psi-Cards can be assembled into a Psi-Challenge marker.
These can be purchased at Cruller's Shop in the main camp area lodge. You'll need to buy these to assemble complete Psi-Challenge Markers out of Psi-Cards.
This is the door you'll use to enter people's minds. Once you have acquired it, you can use it by taking it out of your backpack and pressing 'Y' while in front of certain people.
After you get your Psi-Blast ability you'll start to notice these pop out of defeated enemies and destructibles. They look similar to mental health, but are orange. Collect them to refill the ammo for your Psi-Blaster.
You can use these at any time in a level to pull yourself out of the level. They can be used an infinite amount of times, however, once you've exited you'll start the level back at the beginning, so think twice before you use them!
Thats my name, and technically he's not an item, but this seems like a good place to put him. When you find one of these guys you'll be able to use them to teleport back to any previously visited area in the current mental world.
Inside Vaults are peoples memories. You'll find a few of these in every person's mind. Simply punch a Vault to open it and then you'll be able to view the memories. If you ever want to rewatch a memory you've received you can do so in your journal.