Noita is a game that doesn't give you any sort of introduction or tutorial. Not only it the game very difficult to get into, but also the core aspects of the game are hidden away in secret areas of the world.
One of the main things people are looking to know is how to unlock new spells to use in their wand builds. To unlock new spells in Noita, you need to collect the hidden orbs or solve the secret quests. Every time you collect one orb, you'll gain the spell contained inside it. At the completion of a quest, you'll unlock an entire series of closely related spells.
The easiest orb to get is floating right above the mountain at the spawn of the game. If you manage to get up top via spells, items, or perks, you can fly straight up from the peak and find a hidden floating island. Contained inside the island are an orb, an emerald tablet, and an altar. The alter and tablet are essential to solving quests in the world, and it'll take a lot of experimenting to find out how they both work.
Do you have to unlock spells in Noita?
While unlocking spells is a great option and a way to make the game more interesting, unlocking spells is not a necessity to have fun in Noita. If you have limited amounts of playtime or simply want to casually play the game, it's not really necessary to go around unlocking all the spells.
After hundreds of hours in the game, I still don't have all the spells unlocked, and the only reason I'd go for unlocking the rest is for the Steam achievement. Many of the spells are quite powerful and fun such as the nuke spell, and others such as Greek Letter spells are essential to having long runs and creating the most powerful wands.
Are there permanent unlocks in Noita?
Despite Noita mainly being a roguelike game, it has rogue-lite elements in the form of permanently unlockable items. Besides the items, there are permanent character cosmetics and world changes that'll happen as a result of completing the quests.
However, these permanent changes don't actually affect gameplay at all, with the exception of more spells being added to the in-game shops and randomly generated wands. Noita doesn't have any permanent character upgrades besides cosmetic changes to the player model.
Without spoiling anything, there are 3 small permanent cosmetic unlocks to your character. They're basically badges of honor for the player, showing themselves and anyone watching that they've completed 3 of the hardest challenges in the game. Unlocking the 3 cosmetics will show that you've truly mastered the game.
Unlike the spell unlocks, you can't simply use mods to unlock these. They have to be done in vanilla, unmodded Noita. Once that happens, the player has the unlock on their avatar forever, unless they do the process of reversing that, which is both another secret and a huge spoiler.
If you want to try out alternative ways to play the game, you can always check out the workshop on Steam for tons of cool mods.