You can obviously combine these challenges together/make them easier for yourself. This is just a list of ideas that will be slowly expanding, and I know some people have a hard time finding their own challenges.

Class Challenges are pretty simple to understand.
You choose a specific class (Range, Melee or Magic) and then when you get/are able to get the first weapon of the chosen class, you start your playthrough with only that type of weapon.
You can try this for both normal and hard.
There is nothing more to add so time to get into the next challenges.

• Skipped Convergence (Similar to The 0 Fountain Challenge by Haaxor1689) - This challenge is brutal, you can only use the fountains that were already fixed, and cannot fix any broken fountains you find in the world. Probably one of the hardest ones that will appear on this list.
  
• The 0 Fountain Challenge by Haaxor1689 - Imagine the Skipped Convergence, but now you can only use the fountain in Fairreach. Yeah. Have fun.
  
• Useless Anvil - Beat the game without upgrading any weapons, on hard.
  
• Greedy Kid - No shops, no anvils, no spending money.
  
• Hardcore - One life. If you die, you delete your save. Simple as that.
  
• Badgeless - No badges. No cool synergies.
  
• What is this silver part of the inventory? - You cannot wear any equipment. Which means no rings, no helmets, and no chestplates. One hit probably kills you.
  
• Naked Traveller - No armour, no rings, no badges. One hit probably kills you.
  
• Stupid - Your mind was fried and now you cannot understand complex things. You cannot craft any items.
  
• This pig seems greedy - You do not trust the pig, so you won't unlock any of the banks.
  
• Plum Hater - Every time you get a MEGA PLUM you throw it in the chest and forget about it. No upgrading potions.
  
• Taking the phrase "do not drink" too hard - No potions. >_>
  
• It is clogging my inventory! - You cannot use loot from chests, or enemies. >_>
  
• Unexplored (by Jothanoth) - You can only take the shortest path to the arch pieces and entrances, no deviating from the path.

Rules of the ArchHell Challenge:

• No Special Rings.
  
• No Reparing Broken Fountains.
  
• You can only upgrade weapons to +2.
  
• You can only have 5 badge slots.
  
• Play on HARD.
  
• You can only use one class of weapons.

There are no more rules, and these will get tweaked after a couple of playthroughs of this challenge that I will do in the future.

The user and world record speedrunner, boomstick, released a Archvale world randomizer!
https://noggster.github.io/archvalerandomizer/

I have been reading the suggestions to the challenges you have been giving me, and well, they are terrible. >_>
Now, if you want to suggest an idea for a challenge, think if you can actually beat the game without going insane. Yes, some of these challenges are quite hard, but saying that you should only use the wooden sword is stupid and unenjoyable.
That is it. Thinking of a cool challenge :D