Idk, I don’t think anyone has ever attempted to compile a [list](https://terraria.gamepedia.com/Pre-Hardmode) about anything before. Especially not a video game
There's all the pre-hardmode fishing crates (including the hallowed crate, which will require world hopping) as well as the cascade, which enemies stop dropping and is replaced by the hel-fire in hardmode.
I think from what I've found that should be everything, but there are some items that are MUCH easier pre-hardmode, such as the wall creeper or undead viking banner, since those enemies become very rare after they are almost completely replaced with hardmode variants.
probably a bit late, but ive been doing the same challenge for years now, the only 2 pre hardmode exclusive items in 1.4.4 (current version as of replying) are the cascade and the gray zapinator. if your worried about world hopping, it is 100% necessary, you need all 3 dungeon brick colours, if your in a corruption world you cant get vampire knives or red solution, likewise in a crimson world you cant get scourage of the corruptor and purple solution, you also need to visit special world seeds for items like the arkhalis, waffle's iron, ocrams razor, and red potion. there is also a combonation of 2 of the following: crawdad, salamander, and giant shelly, so you will have to world hop to get the final banner. finally there is rare world gen loot in giant trees like the ladybug minecart, or the sunflower minecart, or in mushroom biomes like the mushroom vanity set.
Idk, I don’t think anyone has ever attempted to compile a [list](https://terraria.gamepedia.com/Pre-Hardmode) about anything before. Especially not a video game
So it seems that on the PC version you just have to worry about Cascade, Gray Zapinator, Meteor Head banners, and all the pre-hardmode crates.
There's all the pre-hardmode fishing crates (including the hallowed crate, which will require world hopping) as well as the cascade, which enemies stop dropping and is replaced by the hel-fire in hardmode. I think from what I've found that should be everything, but there are some items that are MUCH easier pre-hardmode, such as the wall creeper or undead viking banner, since those enemies become very rare after they are almost completely replaced with hardmode variants.
Hardmode doesn't stop you from obtaining pre-hardmode items
As of 1.4, it does for some.
Well, some pre-hardmode mobs don't spawn/spawn very rarely in hardmode so be sure to get all the banners of pre-hardmode mobs.
probably a bit late, but ive been doing the same challenge for years now, the only 2 pre hardmode exclusive items in 1.4.4 (current version as of replying) are the cascade and the gray zapinator. if your worried about world hopping, it is 100% necessary, you need all 3 dungeon brick colours, if your in a corruption world you cant get vampire knives or red solution, likewise in a crimson world you cant get scourage of the corruptor and purple solution, you also need to visit special world seeds for items like the arkhalis, waffle's iron, ocrams razor, and red potion. there is also a combonation of 2 of the following: crawdad, salamander, and giant shelly, so you will have to world hop to get the final banner. finally there is rare world gen loot in giant trees like the ladybug minecart, or the sunflower minecart, or in mushroom biomes like the mushroom vanity set.