Structures

Arco can construct twelve structures and upgrade three prebuilt structures. Some structures have multiple levels that can be unlocked.

House
Arco's house is the central hub where Arco can craft items, food, and potions, and sleep to restore energy or level up. It's implied that any items in Arco's inventory are actually stored in the house, as failing to intercept Bom on his way from a ship to the house results in the critter stealing food right from the inventory!

All house upgrades are available from the start, and can be completed anytime once Arco has gathered the needed resources.

Fields
The three fields next to the house let Arco grow a variety of crops. Fields have three upgrade levels, which impacts the number of crops harvested (except for giant pumpkin which always produces one item).

Altar
The altar lets Arco pray for various in-game effects, once prayers are unlocked as part of Lily's quest line. Arco needs to provide a few items to activate a prayer, which will remain activated indefinitely until it's cancelled or replaced with a different prayer. Only one prayer can be active at once.

Available prayers:

The alter can be upgraded anytime (even before unlocking prayers), but upgrades are cosmetic and have no other effect.

Campfire
The campfire, fire pit, and fireplace can be used to light torches. Arco can also stand next to them to restore health over time if there are no monsters on Deiland. Lighting the fire costs an additional 2x wood each time. The fire is put out by rain, except in the fireplace.

Well
Wells allow trees, bushes, and flowers to be planted around it, and stores water replenished by rain. The water can be dropped onto crops using a bucket, which reduces the growth time by two minutes.

Fences
Fences are built segment by segment and can be used to prevent enemies (but not Bom) from reaching fields or other areas. Gates open for Arco but not enemies. Fences are unlocked by Brram's second quest.

Flower pot
Flower pots let Arco grow a variety of flowers. They're unlocked as part of Lily's quest line. Flower pots have different designs that are selected randomly when you begin placing the pot, but this is cosmetic and has no gameplay effect.

Due to a game bug, flowers will finish growing instantly when you exit and reload the save.

Barn
The barn houses up to four sheep, allowing Arco to collect milk and wool (see the sheep page for more info). Crafting a barn unlocks the straw crafting recipe. Only one barn can be constructed.

Pier
The pier can be constructed on Deiland's lake, and lets Arco catch blue bass and salmon (see the lake page for more info). If Mûn is on Deiland, she'll fish alongside Arco and double each catch.

Mine
The mine is built into the mountain located on the opposite side of Deiland from the house, where the large x-shaped crack is. The mine is unlocked after upgrading the house with a laboratory. Only one mine can be built.

After using a torch to light the static torch post located in the mine, Arco can mine for crystal, stone, metal, silver ore, and gold ore inside. The central pathway is littered with small rocks, which are guaranteed to drop one of those items when broken. Arco can break up to four small rocks until the mine cart is full, at which point he can no longer mine the small rocks until Goliath visits the planet and trades them for metal. The small rocks in the mines can only be mined once, but the rock walls can be mined indefinitely. Clearing the central path allows access to Deiland's crystal heart, which is purely cosmetic and doesn't do anything.

Crystals also spawn on the walls, which can be mined for guaranteed crystal drops and regenerate periodically. A notification in the top-right corner stating "Into the mine!" indicates that the crystals have regenerated and are ready to be collected.