This is a massive grind. You have to get 1 copy of all 120 weapons at once (Basically this will be the last thing you do in the game). Biggest issue is that there are 30 "Recipe" weapons that can only be obtained from trading specific items (or by purchasing for real money (
$$) the "loot boxes"). There are also 11 weapons (I think) that are "free" from the DLC's, but it does require purchasing those DLC's (but as I was unlocking this, I did get a couple of these from the 'Daily Death Streak' - though it might have been because I already had it from buying the DLC's). Biggest hint is to not just trade willy-nilly, but to focus on trading for the recipe weapons. Once you trade for the weapon, you have a random change of that weapon showing up in the Daily Death prizes. For the quickest strategy to farm these, is to repeat the 'Daily Death Streak' as quickly as you can (since this will get you 5 weapons after 13 days plus about 3 more while completing the levels). To do this quickly open this spoiler:
*** Spoiler - click to reveal ***1. Change the date of your system to the beginning of a month (like July 1, 2018) before starting the game.
2. Start up the game and complete the Daily Death, then exit the game
3. Change the date of your system to the next day (July 2, 2018)
4. Rinse and Repeat 2 and 3 until the 13th day to receive the extra 5 weapons
5. Change the date back to the first day (July 1, 2018) and restart the process over again *with the added knowledge of how to solve the 13 puzzles*.
I did this roughly 5-6 times once I realized that it could be done and had gotten all my remaining basic weapons, and it took me about 2 hours (though the first run was probably 40 minutes learning the level, and then the rest of the time was grinding). This way you don't have to wait for a whole day in order to get more weapons.
So far it appears that the Loot/trading system has been upgraded as of Game Version 1.7.1 where it seems to give you random non-recipe weapons that you don't have (instead of duplicates) when you trade. Once you have all the non-recipe weapons you will start getting random duplicates (
again, non-recipe). Earning weapons from leveling up seems to be much more random and may give you a duplicate. More on the details of this (and where I got most of my information on it) can be found from the Steam gamer Bootch here:
https://steamcommunity.com/app/795100/discussions/0/16937958...I have personally found that trading 3 golden weapons can randomly land you a recipe weapon but I've also gotten a regular gold weapon with the same trade.
There is a great guide from Bootch for all the weapons and their recipes here:
https://steamcommunity.com/sharedfiles/filedetails/?id=13652...but to save you some hunting, Here are the recipe weapons:
*** Spoiler - click to reveal ***Pick Axe: Battle Axe + Crowbar + Ice Pick
Rapier: Combat Knife + Crowbar + Firepoker
Cattle Prod: Crowbar + Flashlight + Wrench
Didgeridoo: Splitting Axe + Microphone + Log
Sledge Hammer: Club + Dumbbell + Claw Hammer
Katar: Brass Knuckles + Combat Knife + Sickle
Toilet Plunger: Cane + Purse + Splitting Axe
Harpoon: Javelin + Firepoker + Pool Cue
Briefcase: Garden Shears + Coffee Pot + Purse
Utlra Great Sword: Battle Axe + Claymore + Broadsword
Splattering Ram: Battering Ram + Pipe + Baguette
Longboard: Skateboard + Baseball Bat + Canoe Paddle
Chopsticks: Log + Kitchen Knife + Teapot
Tower Shield: Kite Shield + Round Shield + Car Door
Magic Tome: Tome + Magic Sword + Ruler
Paint Roller: Claw Hammer + Baguette + Briefcase
Trident: Pitchfork + Rake + Billy Bass
Nail Gun: Power Drill + Wrench + Spiked Bat
Skillsaw: Power Sander + Butcher Knife + Cattle Prod
Weedwacker: Skillsaw + Power Drill + Power Sander
Hell Sword: Laser Sword + Torch + Sickle
Crystal Staff: Oak Staff + Tome + Round Shield
Anvil: Cinder Block + Dumbbell + Battering Ram
Golden Machete: Machete + Katana + Candlestick
Golden Toilet Seat: Toilet Seat + Toilet Brush + Golden Crowbar
Flame Machete: Machete + Flame Axe + Hell Sword
Flaming Toilet Brush: Toilet Brush + Torch + Hell Sword
Ice Machete: Golden Machete + Ice Pick + Ice Harpoon
Electric Machete: Machete + Electric Chainsaw + Cattle Prod
Electric Chainsaw: Chainsaw + Cattle Prod + Flashlight
Unlocking this achievement will also guarantee that these achievements will unlock along the way: well: