DEEEER Simulator: Your Average Everyday Deer Game

There is a cheese method which makes this boss fight easy.

UNLOCKING THE FIGHT
First off you will need to get to the future, then you will find the hamsters near the tower in front of the police station. Directly under the tower are some humans pushing a mechanism. Kill the humans and the hamsters until the white lit tubes go dark. Now in between the tower and the Police Station is a monkey.

Gear up to fight the monkey, lightsaber is recommended
guides on TA show how to get lightsaber

NO DAMAGE / CHEESE
Without doing any damage to the monkey, jump behind it. There are some neon/black rectangles, which the monkey sits on. If you get behind it and take a slight step back but remain on the rectangle behind the monkey. (the slight step back allows for all the weapons to do damage, as when to close they dont all trigger.) Facing the monkeys butt, hold RT, the fight should end in 15 seconds.

VIDEO OF ME DOING CHEESE METHOD (LIGHTSAbER NOT REQUIRED)

Do this at the end of the game in the future with the dragon. Kill the rodents and the humans that push levers to cut the power. Go behind the monkey and spit fire at it. Dont stop pressing the fire button.

If you are interested in a very fast guide :


Timestamps:

00:00 Intro + Self-sacrifice Achievement
00:59 Story Present + Town Musician of Bremen Achievement
04:08 Story Future Ending 1 + 13th Deer Achievement
07:23 Story Future Ending 2 + The Trudeer Show Achievement
08:49 Counting Sheep, Deer-hunting Achievements
09:18 Dead or Deer Achievement
09:33 God Disguised as a Cow, Kept you Waiting? Achievements
10:19 100% BEEF Achievement
10:47 Like a Truck, Dunkleosteus Achievements
11:20 The Devine Move Achievement
12:30 Genius Achievement
13:19 Rhinosaber Achievement
13:49 Big Time monkey. I am Deeeer Achievements

After defeating the Koala (Like a Truck (70G)) and Giant Fish (Dunkleosteus (70G)), use the teleporter to enter the second area. Again, you should find a dragon to ride in this area. Use it to destroy the two hamster wheels and all the people pushing the poles across from the police station. This will cause a giant cymbol wielding monkey to spawn in. Easily defeat the Big Time Monkey using your dragon's fire breath.


Timestamps:
00:00 - Intro
00:20 - Self Sacrifice Achievement
00:48 - Dead or Deer Achievement(Start)
01:00 - Deer Hunting Achievement (Start)
02:05 - Counting Sheep Achievement (Start)
02:46 - Dead or Deer Achievement (Unlock)
05:36 - God Disguised as a Cow Achievement
06:15 - Kept You Waiting? Achievement
09:00 - Town Musicians of Bremen Achievement
11:55 - Deer Hunting / Counting Sheep Achievement (Continued)
15:15 - Counting Sheep Achievement (Unlocked)
15:50 - Deer Hunting Achievement (Unlocked)
19:50 - Final Boss Fight
23:10 - The Trudeer Show Achievement
26:10 - Like A Truck Achievement
26:50 - Dunkleosteus Achievement
27:10 - 100% Beef Achievement
27:40 - The Divine Move Achievement
29:05 - Genius Achievement
31:20 - Big Time Monkey Achievement
32:28 - Rhinosaber Achievement
33:23 - 13th Deer & I Am DEEEER Achievement

There's a building with 2 hamster wheels and guys powering it. Destroy the hamsters and guys to stop the power and a Monkey will spawn across the street. Kill the monkey for the achievement

1:40 Hit By Truck
2:15 Deerify 10 Humans
2:30/13:35 30 Guns
3:45/ 14:20 100 Sheep
6:45 Ride the cow
7:20 Ride Metal Deer
8:10 Doggo Boss
17:50 True Ending
27:50 Giant Koala
28:10 Giant Fish
28:30 4 Burgers
29:00 Cowthello
31:25 Animal Puzzle
33:05 Big Time Monkey
33:35 Defeat Rhinos
36:15 Average Ending

Achievement Walkthrough:

In stage 2 in front of the big rhino there are 2 Gerbils in wheels and 4 groups of people pushing the wheel in the middle. Kill them all and the lights will shut down. Behind you will spawn the monkey sitting down. Kill him and the achievement is yours.