Greetings. This is an evolving guide that I will update as I get better at the game identify further information, be it through personal experience or helpfully donated from people in the comments section. *cough* Please feel free to suggest edits and updates on any of the contents in this guide!

As is said in the description, I recommend playing through the game before reading this guide. Knowing these enemies entering the game can remove the fun of figuring out what each enemy does on your own! With that said, lets continue.

Within this guide will be multiple categories of enemies. Each enemy will be sorted into a category based on their behavior. The categories that will be used are as follows:

-Formation Units
-Soloists
-Ground Units
-Munitions

The categories should be self-explanatory, but for clarification:
Formation Units refers to the common squadrons that fly in formation. This category makes up a majority of the fodder sent at Utopia, including the polygonal "Cheval de Frise," Centipede Squadrons, and other fighters.

Ground Units is a relatively small category and includes enemies that (usually) crawl towards the city from the ground.

Soloists include many of the larger enemies, and usually come into the battlespace alone, or with a pair. They are often tanky, make a neat explosion upon death, and have many abilities.

Munitions includes the secondary destructible projectiles launched by other enemies. None of these spawn on their own, instead being launched from various enemies (usually Soloists, but also formation enemies when formed up.)

Final footnotes: When applicable, names for enemies will be determined from Developer-released lists. This will likely be why some names will be confusing (For example, what is a Cheval de Frise?) Additionally, questions in parenthesis (such as 'when?') indicate locations that need clarification, such as specific days for spawning or specific statistics.

I hope this is helpful.

Formation Units frequently appear in chains, swerving around the arena before settling into a hexagonal cluster and dropping their munitions. When enough constituents of a formation are destroyed, remaining members will attempt to flee the battlespace while dropping their payloads.

Individual formations are usually made up of one type of unit, however on certain days (random or set?) "mixed" formations may appear; These formations include different types of units and can be faster or slower depending on the member units.

Formation Score Bonuses:

• No Escape (Prevent any enemy from despawning offstage)
  
• Annihilation (Destroy a full formation without a nuke)

Fox
Foxes are one of the first enemy types that appear. They are weak but agile fighters, which beeline in a chain formation towards a central area of the battlespace before dropping Class-I bombs innacurately towards the city. Low threat and an easy source of points.

Past Week 2, faster and stronger Red-colored variants appear with Cats. While weak on their own, Cats are much deadlier (see below.)

Axe
Axes are another enemy that is introduced early on. Similar to Claws and Foxes, Axes wind around the arena before forming up above the city and dropping Class-I bombs.
As time goes on, colors switch and gradually becomes more durable and faster.



Claw
Claws are similar to Foxes and Axes, however are much more chaotic in their movement during approach and escape. They are fast, slightly more durable and swerve across the stage while dropping Class-I bombs before either forming up or leaving the battlespace.

Over time changes color and becomes more durable and faster.

Bomber
Bombers are dangerous formation fighters that begin to appear past Week 3. They appear in particularly large numbers and, in combination, rapidly drop Class-II bombs. Class-II bombs are detailed further in the Munitions section, but these upgraded munitions cause Bombers to become a very dangerous unit without nuclear weapons (such as in a hermit build.)


Micro Fighters
Micro Fighters come in many colors. However, they are all very similar, with only minor differences between colors - varying in speed and flight pattern. They are occasionally spawned by certain Soloist units as minions. In general, are very fast.
Notably, upon appearing is invincible for a brief time.

Changes color, increases health, and becomes faster as the days go by.


Ghost
Ghosts appear later in Week 1, and function similarly to Axes, Foxes and Claws. They are fast, and curve around to get into position. Drops Class-I bombs.

Past Week 2, they gain the ability to cloak, making them a more persistent bombing threat.


Cat

Very dangerous formation enemy. Starts to appear along with red Foxes in Week 3+. Fast and durable. When in position, launches Block-II missiles rapidly. These missiles are very fast, and especially with the frequency of launches can easily end a run. Take out ASAP.


Rebels
Rebels come in three variants. They can appear either by themselves or with a mixed squadron; They are most frequently seen in said mixed squadrons. They launch Block-II missiles infrequently, which can be dangerous. When not in formation, they swerve around the arena randomly. This can lead to them flying straight into the ground, a nuclear fireball, or even straight at the city.

Rank 1

Rank 1 Rebels appear during Week 1-2. They are uncommon, but durable and launch dangerous missiles. They have standard behavior. During Berserker, they should be targeted before they launch their missiles or potentially ram the city.


Rank 2

Rank 2 rebels start appearing from Week 2(?) and onwards. They are similar to Rank 1 rebels, however they have a shield that reflects railgun projectiles and protects from nukes.


Rank 3

I have not encountered Rank 3 rebels yet.


The following units follow different flight patterns compared to the above "standard" formation fodder. They will not appear in mixed squadrons or follow the same hexagonal formed-up position.

Cheval de Frise

Another common enemy type appearing from the start to the end. There are many variants of these, with different forms and functions. They appear in large polygonal formations (such as triangles, hexagons, squares) and slowly gyrate downwards, oftentimes hitting the ground but other times dealing large amounts of damage to the city if not destroyed.



Week 1: Blue, Slow and weak. Easy for points, destroy entire squadrons to get good combos.








Week 2, Day 11+: Blue and Plus-shaped. Stronger and faster, but still simple.









Late (when?) Week 2: Orange and original shape. This version is highly durable and explosive. These can absolutely destroy utopia if not dealt with appropriately! Rather than blazing through an entire chain, destroying orange-rank Cheval requires focusing down an individual link in the formation. This will cause a chain reaction, usually blowing a majority of the formation. Prioritize destroying downwards-flying segments, this will be more effective at destroying the formation.

Week 3+: Purple, Sawblade-shape. Strongest and fastest, back to simple but still dangerous.



Centipede Squadron
Centipede Squadrons are formations of hexagonal machines which trail each other in a grid-like chain formation. They will wind back and forth across the battlespace, getting closer and closer to the city, before ramming the shield.

Over time gains speed and durability.

After Week 2 (When?): Notable variation may appear, invulnerable save for the head segment. Upon destruction of head, detonates the rest of the body. Very durable but not as aggressive, may wind in a less consistent manner not directly towards the city.


Cosmic Anemones

Glowy invertebrates usually spawned by Nullifiers, Anemones may also spawn in similar fashion to Cheval de Frise during late Week 3, albeit in an expanding and contracting nature. This makes them harder to shoot down.
They will sap shield energy or Population when reaching close proximity to the city.

Asteroids











Very strenuously put into the Soloist category, Asteroids fall from the top of the battlespace towards the city. Durable, and upon breaking split into further asteroids. There are many sizes, and the smaller the asteroid, the smaller the fragments. Low threat, asteroid fragments may change trajectory away from the city when the parent asteroid is destroyed.
Linked Achievement: Trainspotter

X-Tanks are the first soloist enemy to appear, and serve as "bosses" during Week 1.
They are durable and launch Block-I missiles that can, in numbers, overwhelm city defense if not prepared. X-Tanks usually fly high above the city, hovering and swerving between sides of the battlespace after launching salvos of missiles. They can be easily destroyed by detonating their missiles next to them.

There are three main levels, with rank quickly escalating over Weeks 1-2:

Rank 1:
Purple-colored, Rank 1 X-Tanks are the weakest of the three, and only appear during Week 1. They are quickly replaced by Rank 2 tanks. They launch one Block-I missile each salvo, and are simple to take out.




Rank 2:
Red-colored, Rank 2 X-Tanks are a notable threat due to their frequent launches of multiple projectiles. They are more durable, and launch salvos of 2 Block-I missiles every couple of seconds. Begins to spawn at the end of Week 1.




Rank 3:
Blue-colored with a different shape, Rank 3 X-Tanks switch up the standard behavior; In-between salvos of missiles, Rank 3 X-Tanks will activate a shield for a short time that reflects railgun projectiles (This shield can be broken with sustained firing) and spews out swarms of suicidal red micro fighters. It otherwise behaves like a Rank-2, firing pairs of Block-I missiles.



Gorilla
Large orange, helm-shaped machine similar in behavior to an X-Tank. It is very durable, flying either close to- or far away from the city. It launches Block-III missiles frequently, and is very dangerous if left unattended.






Squids are cloaking aliens with multiple abilities. There are three types, becoming more dangerous over time with more abilities. They will fly down from the top of the battlespace, either cloaking or beginning an attack. When cloaking, they will eventually re-appear and start charging an attack with an energy pulse. This pulse cannot damage or destroy an unshielded city by itself, however it can destroy Laser Watchtowers and the city shield.

Squidling
Squidlings are the weakest rank of squid, only able to damage shields with their attack.
Primarily appears in later Week 1.





Squid
Squids are similar to Squidlings. They deal large amounts of shield damage, or can temporarily disable the city railgun. More durable than Squidlings.

Spawns during Day 11+.




Pulse Squid

Pulse squids are a notable variation from previous squid ranks. Rather than charging up an energy beam, they instead appear and drop unique pulse bombs. These bombs are difficult to shoot down and do not leave a lingering nuclear fireball; Instead, they deal direct damage and push away other weapons. They begin to spawn during Week 3(?).

Wizard

The Wizard is a dangerous elite. It spawns after Week 3(?) and drops Class-II bombs between appearances. It hovers towards the top of the battlespace, and occasionally cloaks away from danger. Its released bombs are very dangerous, particularly with the many other enemies that spawn during Week 3.


Cruiser
I don't have much information. Likely spawns after Week 4. Flies high above the city, laying a line of guided "Gnat" bombs which fly towards the city. Very dangerous.
Linked Achievment: Not Today Thanks

Albert

Its Albert! Occasionally appears during Week 1-2(?). Hovers high above the city, creating individual green micro-fighters that work their way down to the city. Not very dangerous, and leaves after some time. Accompanied by a spooky sound effect when appearing, and gives a nice score boost if killed.
Linked achievement: Its A Shiny!

Obelisk

Large red totem of destruction. Extremely dangerous, spawns in a pair and rapidly launches Block-III missiles towards the city. Extremely durable, capable of eating many nukes. Floats above the city. Spawns after leaving enemies alive for ~40 seconds, any week.
Linked Achievement: Obeliskos

Calamari Mothership
Very strong boss-like alien mothership. It appears at the end of Week 2, and acts as a gateway boss between Week 2 and Week 3. It frequently switches sides of the upper battlespace, dropping multiple Class-II bombs and creating a strong shield while emitting fast, green, suicidal Micro-fighters. It can survive multiple nuclear blasts. Upon death, splits into many fragmentations which fall to the ground.
Linked Achievment: Calamari Fritti






Nullifier

Floating slime-bag. Not very dangerous on its own, absorbs nuclear fireballs in a radius around itself. Upon absorbing enough energy, explodes into a swarm of cosmic Anemones which coalesce around the city, draining shield energy or Population.
Linked Achievment: Seafood Platter

Giant Blob
Giant blobs appear in the beginning of Week 2(?). They are durable, resistant to nuclear weapons and slow. They slowly crawl towards the city to deal collision damage.






Weeds
Weeds begin to appear towards the end of Week 2. They come in larger quantities than Giant Blobs, but are similarly durable and resistant to nuclear weapons. They have the same behavior, but are slightly faster.

Past Week 3(?): Weeds upgrade into a green form, which is more durable and faster.



Gorilla Tank

Gorilla tanks are similar to their flying cousin, but are ground-bound and inch toward the city. They begin to appear later in Week 2-3.

Bombs constitute unguided munitions that are dropped (innacurately). There are two types:

Class-I Bombs
These are dropped by most fodder enemies. Smallest type of warhead, with little durability and small nuclear explosion. Prioritize missiles and other bombs.

Past Week 2: Class-I bombs are upgraded to a pinker variant. There is little functional difference, upgraded bombs are simply more durable.

Class-II Bombs
Class-II bombs start appearing at the end of Week 2, and are first encountered when fighting the Calamari Mothership.
These bombs are invulnerable to conventional attacks and will not be targeted by automated defense (such as Laser Watchtowers or Plasma Flail). They can, however, be pushed away from the city by the railgun, or detonated by other nuclear explosions.
Class-II bombs have larger payloads than other munitions with a radius similar to a Block-III missile, and are extremely dangerous if not detonated early by other nuclear weapons. (This is especially important for Hermit runs!)


Missiles constitute guided explosives, similar to bombs but far more dangerous due to their guided nature.

Block-I Missiles
Block-I missiles are the primary weapon of X-Tanks, with no(?) other enemies launching them.
They are slow compared to other missiles, but faster than bombs and more dangerous due to their accuracy. They have an explosion that is slightly larger than Class-I bombs, and accelerate quickly after launch.



Block-II Missiles
Block-II Missiles are less common than Block-I missiles during Week 1. These are otherwise very similar to Block-I missiles, the main difference being faster top speed and acceleration. They are usually launched by stronger fodder enemies such as Rebels and Cats. Due to their speed, they should be taken out quickly.

Block-III Missiles
Block-III missiles are likely the most dangerous type of missile. They are launched by the strongest enemies, such as Gorillas, Tanks and Obelisks. They are much slower, but much more durable than other missiles, with a much bigger explosion (comparable to a Rationed Warhead.) Due to their health, the railgun will have noticable knockback which can be more effective than finishing off the warhead.

Yours Truly, Significant Harassment (Aka Onezero0)
John

Todo:

• Clarify Spawn Times
  
• Standardize Entries
  
• Add Images
  
• Clarify Other Things