Couldn't really think of a good name for these.
"Treasure Hunter" Achievements: basically, these are achievements that give absolutely no reward (including no reward on Steam), they are simply an extra set of very hard-to-achieve achievements for you and your friends to brag about, and for completionists to grieve over. Simply accolades, if you will (maybe even give them as Artifacts, or perhaps even little Accessories, although the intended effect was to have no reward). These would only be able to be obtained in the Arcade, not missions. Some examples of these types of achievements would be something like:
- Elegantly Designed: Complete Tier 1, Depth(s) 0-7, without taking damage (self-damage from Fang of Vog, Faust, and Gran Faust do not count as taking damage, but getting hit by explosions you caused or a pot you threw etc do count)
- A True Veteran: Complete Tier 2, Depth(s) 8-17, without taking damage (self-damage from Fang of Vog, Faust, and Gran Faust do not count as taking damage, but getting hit by explosions you caused or a pot you threw etc do count)
- A Terror Unknown: Complete Tier 3, Depth(s) 18-28, without taking damage (self-damage from Fang of Vog, Faust, and Gran Faust do not count as taking damage, but getting hit by explosions you caused or a pot you threw etc do count)
- Absolute Perfection: Complete the entire Clockworks, Depths 0-28, without taking damage (self-damage from Fang of Vog, Faust, and Gran Faust do not count as taking damage, but getting hit by explosions you caused or a pot you threw etc do count)
- Melt the Competition: Complete the Gloaming Wildwoods using only Elemental weapons (weapons with split damage, such as Divine Avenger, are allowed. Additionally, your Sprite must have the correct Harness, or you must remove your Sprite)
- Poking is the New Dicing: Complete the Royal Jelly Palace using only Piercing weapons (your Sprite must have the correct Harness, or you must remove your Sprite)
- Scissors Beats Rock: Complete the Ironclaw Munitions Factory using only Piercing weapons (your Sprite must have the correct Harness, or you must remove your Sprite)
- A Dark Hour: Complete the Firestorm Citadel using only Shadow weapons (weapons with split damage, such as Acheron, are allowed. Additionally, your Sprite must have the correct Harness, or you must remove your Sprite)
- Bringing the Pain: Complete the Ultimate Gloaming Wildwoods (Rabid Snarbolax Shadow Lair) without needing to revive (including Emergency Reviving)
- A Royal Problem: Complete the Ultimate Royal Jelly Palace (Ice Queen Shadow Lair) without needing to revive (including Emergency Reviving)
- Fueling the Fire: Complete the Ultimate Ironclaw Munitions Factory (Red Roarmulous Twins Shadow Lair) without needing to revive (including Emergency Reviving)
- Slayer of the Corrupted: Complete the Ultimate Firestorm Citadel (Darkfire Vanaduke Shadow Lair) without needing to revive (including Emergency Reviving)
- What's the Number?!: Defeat Snarbolax using only regular Catalyzer shots
Just one of those simple things that probably wouldn't be too hard to add and would give people something to work for if they wanted to.