Some starting notes, so you can be more confident moving forward.

• There are no missables as the game can be replayed over and over without revisiting EVERY level.
  
• I also played this game on 2-player co-op the entire time and cannot confirm anything relating to singleplayer.
  
• One "game" consists of going through ANY five levels you choose.

Counters to be aware of:

• 500 Chompies Killed (Cannot confirm if other enemies count)
  
• 1000 Meters Traveled while carrying a Pig (via Gravity Gloves)

Achievement Notes

• Hosts cannot earn 'Survivor' or 'One Upsmanship'. Simply switch hosts and perform the task again to earn it for the other player.
  
• The 'I Am A Pumpkin King' achievement is NOT restricted to Halloween. You can find it listed under Start Game --> Minigames. If you do this while quitting a game you're hosting, you will actually enter the minigame as a team instead of solo.
  
• Most counters are updated at the end of each stage as opposed to real time.

Hosting Notes

• If you happen to leave a server, or stop hosting, you will probably have to restart your game in order to join another game or host another properly.

Game Layout

1. Host a game
   
2. Select 5 Stages (First time may be random)
   
3. Beat the 5 Stages
   
4. Arrive at Escape Area

Big Spender
Spent some turnips.


I don't know if buying health during levels counts, but you do indeed spend turnips.

Alternatively, I can confirm that buying hats and skins at the beginning of each game will net this achievement. Turnips are dropped by enemies. Easily farmable in the challenge section, though you only need 20-35 for the cheapest items.

And Pigs Might Fly
Found the final piggy.


In the escape area after beating a game, trigger the home (house) buttons to start the credits. DO NOT SKIP THIS SCENE. At the end of the credits, a pig will hover across the screen unlocking this achievement. If one player skips the credits, it'll skip for all players regardless of being a host.

Challenger
Complete all the challenges


Ultimate Challenger
Did all the challenges in 1 run


Challenges are all located in the escape area to the right. You will lose your party horn.

Oddly enough, in my game, I couldn't actually pass any levels that I had already beaten, so Challenger and Ultimate Challenger are practically one in the same. Even if the levels aren't reset, simply do them in order and the achievement will unlock anyways.

Each challenge is 30 seconds of surviving, and you get healed after each challenge.

Challenge 1: Shotguns
Straightforward, 3 bullets per chompy to kill, don't get hit twice.

Challenge 2: Pitchfork
Probably the hardest one for me, each chompy takes 2 hits to kill. Stick together, otherwise one or the other player will get swarmed. Pitchforks also hit multiple enemies. If you stick together, then one hit each by a player will take out a chompy making it easier to clera them out.

Challenge 3: Laser
Uh yeah, be careful when picking up the lasers. You might unsuspectingly kill your teammate. The best strategy is the corner strategy. Due to the obstacle, one player can cover one end and the other can cover the other end. Have not had a chompy spawn in the top right corner.

Challenge 4: Gassed Shotguns
Like the first stage, except you can't aim as well. It's best to keep moving and dodging and getting kills when you can. If you can create a kiting scenario, it'll be easier to survive.

Challenge 5: Lasers w/ holes
Same as the third challenge, literally.

If you complete this without any issues, both achievements should unlock.

Dismantler
Kill 100 chompys


Mass Dismantler
Kill 500 chompys


If you haven't earned this by the time you finish the game, there's two ways you can farm this. The first would be to replay 'Mind Your Step' clearing out all the enemies then dying at the end. The second would be to make it all the way to the escape area and play the challenges over and over. (See Challenger for more information).

Kills are counted individually.

Pig Carrier
Carried the pig 1000 metres


LEVEL: THE GLOVE

Another grind achievement. Easily farmable on 'The Glove' level. Simply doing the mission and then walking the pig from the exit to the front and back twice should net you at least 200 meters. So repeat that a few times and then turn in the stage and the achievement should unlock.

Survivors
Got to the end of the game with no deaths.


You simply have to complete 5 stages (pick the 5 easiest), without dying once. If you restart, I would just rehost to be on the safe side. Unlocks when you reach the escape area.

Host will NOT get this achievement.

One Upsmanship
Killed more chompys than your friend in a game.


Like Survivor, this does NOT work for the host.

Simply score more kills than your host and you'll get the achievement upon entering the escape area. The scoreboard at the very bottom will tell you how many kills each player got (hopefully, there seems to be a bug with that scoreboard sometimes with a failed request).

Chameleon
Played as another character.


Simply do not start a game as 'Steve'.

Party Animal
Made it to the end of game party



Simply beat 5 stages and you will arrive at the escape area, or the end of the game.

Peaceful Farmers
Made it through The Grind without getting the weapons.


LEVEL: RUN!

In the stage 'Run!', you must not pick up the Shotguns at the start of the level and then traverse to the very end where there's a grinder portion.

The grinder portion simply consists of running to the right avoiding enemies and obstacles. At the last bit before the exit, you must take the upper path as the lower path is blocked by a barrel that you cannot shoot anymore.

Run For Your Life
Escaped The Grinder


LEVEL: RUN!

Simply complete 'Run!' stage.

Miscommunication
Got killed by a mine when not wearing the goggles in Helpful Chums


LEVEL: HELPFUL CHUMS

In 'Helpful Chums', simply walk around the warning yield signs until you explode. Only the person who dies get the achievement. Cannot confirm if other player has to be wearing the goggles.

Explorer
Found the funny face mask.


LEVEL: MIND YOUR STEP

In the level 'Mind Your Step', head north til you find the shotgun. Shoot the explosive barrels to the top left of that area and simply walk into that alcove for the achievement.

A Chompy In Hand
Killed 3 chompys at once with potato bombs


LEVEL: BOMB IT!

In 'Bomb It!', get near the end where you have an arena that spawns three enemies. Have the player with the potato launcher setup 5 potatoes where the 3 enemies spawn. They all spawn on the left side, about one tile from the wall in a vertical line.

Then the player with the detonator walks in and blows them as they spawn. If all three die, the achievement will ONLY unlock for the player with the detonator.

Tidy Farmer
Killed all the soldier bots in Cross Fire


CROSS FIRE

Simply play 'Cross Fire' and kill all the robots circling the middle pathway. Complete the level to trigger the achievement. (You can stand on those pipes, at the bottom right area)

We Like Pies
Didn't let the Pieosaurus die.


LEVEL: 3.1415926

The Pieosaurus appears on more than one level, but the level that DOES matter is the '3.1415926' level. The majority of the level is pretty easy until you get to the laser part at the very end.

The player with the pie maker should never release their pie machine.

The portion where the paths split up momentarily, have the player with the gun stay down with the pieosaurus when he walks over the button. 4 enemies will spawn as all buttons are pressed. Two to the left, and two to the right. The user with the gun should take out the two closest to Pieosaurus before working on the two that spawned closer to the player.

After that, you'll reach the laser portion. Overall, it's simply because the pieosaurus fits in between the lasers rather well. The user with the gravity gloves should simply help the pieosaurus by alternating the pig blocks to block the lasers.

The pie user can stall the pieosaurus by making him go up/down in between lasers, whichever way has more room.

Lazy Farmer
Made it through 'Pig Weapon' with one set of gloves.


LEVEL: THIS LITTLE PIGGY

One player will simply pick up the glove while the other will not. Fairly simple. The first portion, simply use the first laser to kill all the enemies around the 6 buttons.

The second part, have the player without gloves stand near the first laser. The player with gloves will bring both pigs to the lasers at the end. When blocking the second laser, enemies will spawn to your left. Simply move the pig block of the first laser (far left) to unblock the laser and have all the enemies run into that laser. Complete the level to unlock the achievement.

If both players are present near the lasers, the enemies will spawn when picking up the second block making it difficult to make it over to the laser.

Time to kill
Made it through Bomb Hats without collecting all the clocks.


LEVEL: BOMB FOR HATS

Overall, your paths are split. The player on the left will pick up every clock they see. The player on the right will skip ONLY the very first clock. Beat the level per usual and the achievement will unlock for both players.

DRINK!
Made it through the discotheque.


LEVEL: DISCO DISCO DISCO DISCO

Simply complete the level 'Disco disco disco disco" for this achievement.

While it is a bit tough to do, the hardest part is the end where you enter the 'disco'. The enemies there are NOT teleporting. There are two sets of enemies and you can only see one set at a time. Each time it switches, you'll see the other set and vice versa. So if you can visually see where the other set is, making it through to the end is no issue at all.

Take It To The Max
Escaped The Extreme Grinder


LEVEL: GRINDING TO THE MAX

In the stage 'Grinding to the Max', you will play the harder version of 'Run!'. This is probably the hardest stage to complete with achievements in mind.

Instead of Shotguns, you will have lasers. You will also be gassed making controlling your lasers VERY difficult. At the end, the grinder portion will strap a bomb to you and you'll have to escape while picking up the timers.

The hard part? The clocks are technically broken. If the top clocks are collected after the lower clocks, then the top clocks MAY bug out and not reset the bomb timer to 10 seconds. The person who steps on the switch should take the bottom clocks. The other person will take the two top ones.

The player who takes the top clocks should skip their third clock and let the bottom player take it. You'll have enough time to stretch for the next clock.

I Am The Pumpkin King
Unlocked Franky in Attack Of The Vegtabots


Not holiday restricted. The Survival Mode can be accessed through Start Game --> Minigames (Single player) and Halloween Survival.

Now, unlocking Franky is a matter of time, and not score. If you go into this minigame after hosting a game, you will actually enter this game in MULTIPLAYER instead of SINGLEPLAYER making it easier to beat.

You will unlock Vampy first, then Franky second. The total score should be roughly around 8500-9000. In terms of time, it's roughly a minute or two after the gas tank spawns and messes up with your aim. If one player dies, that dead body will attract SEVERAL enemies to them. DO NOT KILL THESE ENEMIES. That's less enemies that's on you. Simply kill the pumpkins, and kite in a circle to cruise to victory.

There is a chance that the achievement does NOT unlock at the end. Simply restart the game to force a check of the player owning the Franky character thus unlocking the achievement.