There are 6 characters total, Mr. Lucky already starts unlocked, and the other 5 can be easily unlocked by acquiring max upgrades during any run:


Nerdy
Unlock Nerdy rat
Nerdy is unlocked by acquiring the Star Ally VII upgrade during a run.


Soldier
Unlock Soldier rat
Soldier is unlocked by acquiring the Ammo VII upgrade during a run.


Doctor
Unlock Doctor rat
Doctor is unlocked by acquiring either the Poison VII or Curse VII upgrade during a run.


M1C3
Unlock M1C3 rat
M1C3 is unlocked by acquiring the Arrow VII upgrade during a run.


Mr. Shock
Unlock Mr. Shock rat
Mr. Shock is unlocked by acquiring the Lightning VII upgrade during a run.

Next up we have 9 achievements tied to winning a run, i.e. beating wave 30. Don't forget to use your cheese and buy the global and character specific tree upgrades to make it easier!


Mr. Lucky Win
Clear the 30th wave with Mr. Lucky


Nerdy Win!
Clear the 30th wave with Nerdy


Soldier Win
Clear the 30th wave with Soldier


Doctor Win!
Clear the 30th wave with Doctor


M1C3 Win!
Clear the 30th wave with M1C3


Mr. Shock Win!
Clear the 30th wave with Mr. Shock


Untouchable Rat
Clear the 30th wave without taking any hit


Immovable Object
Reach the 30th wave without moving
Just don't touch the movement keys!... or the controller stick ;)


Vanilla Rat
Clear the 30th wave without any tree skill
This is a tricky one! You can disable a tree upgrade by simply clicking on them, both in the global (computer) and character specific (cheese wheel) trees! For this achievement, you'll need to beat a run without any of the character specific upgrades, global upgrades can (and should) still be used. Either way, this is one of the most annoying achievements and might take you some tries, I've personally done it with Mr. Shock cause of his good base gun, but try it with the character you're the most comfortable with. Good Luck!

There are 8 achievements tied to the upgrade trees, 7 are tied to the character specific trees, in the cheese wheel and 1 to the global tree, in the computer. To buy said upgrades you need cheese, -this game's currency- the Cheese X rare upgrade that makes enemies drop 50% can be a big help for these, speeding up the process greatly, but either way you'll eventually be able to buy them all.


Max Mr. Lucky
Buy all tree skills from Mr. Lucky


Max Nerdy
Buy all tree skills from Nerdy


Max Soldier
Buy all tree skills from Soldier


Max Doctor
Buy all tree skills from Doctor


Max M1C3
Buy all tree skills from M1C3


Max Mr. Shock
Buy all tree skills from Mr. Shock


The All Knowing
Unlock all tree skills


The Ecletic
Unlock all global upgrades
For this one, you don't need to max out all of the global upgrades, simply buying the level 1 of all of them will do.

These are 8 miscallaneous achievements that didn't really fit in any of the other categories, hold tight cause we're getting close to the end!


Luck Essence
Have 5 or more rare upgrades in a single run
If somehow, for some reason, you are struggling with this one, Mr. Lucky and the global tree have some upgrades that increase the rare cards chance, but this should be the first achievement you ever get!


Cheese Maniac
Spend 30,000 cheese coins


This Is My Highest Point
Get the Gear V upgrade
Don't worry just keep playing and you'll get it soon!


Infinite Ammo... Or Almost.
Have 80 or more ammo

This one is most easily done with Soldier, following the left upgrade path. Simply focus the Ammo upgrades and you'll get it in no time! Gear II and V will also help.


Machine Gun
Shoot 10 or more shots at once
This one can be done in multiple ways, a pretty consistent one is probably following the same Soldier path as the last achievement, and focusing on upgrade cards such as Ammo VI, Impact VI and VII, Gear IV and V, as they all give more bullets, on top of all that you can also go for the Critical V upgrade (everytime an enemy dies to a critical hit, your next shoot will have 1 more bullet), just make sure you're also strong enough to not lose!


A Very Big Heart
Have 10 or more full hearts


Pretty simple, fully upgrade and grab the global hp upgrade and follow M1C3 middle path, this alone will get you to 8 whole hearts, now just go into a run and get to Health III, this will get you to a total of 11 hearts, and unlock the achievement.


Are You Okay?
Die in the first wave
Make sure you are not using the global hp upgrade, Nerdy's gun doesn't have auto-aim so grab Nerdy and do your best to miss all the enemies in the first wave while you run at them repeatedly.


Cassino Powers
Roll 10 times in a single round

With the global extra roll upgrade active, grab Mr. Lucky with this upgrade path and just play normally, when reaching the last few waves just spam reroll and you should get the achievement, if you somehow still lose against all the odds, try again and should be good!... hopefully.

This one is actually a misc. achievement as well, but it really really needs 2 whole categories, this achievement is probably the one that will take you the longest to unlock, for a good reason. Here I'll do a quick rundown of all the upgrades, good luck and have fun!


The Collector
Choose every upgrade available at least once

Normal Upgrades

1. Increases projectile damage by 20%.
   
   
2. Increases projectile damage by 30%.
   
   
3. Increases projectile damage by 30%.
   Increases knockback by 50%.
   
   
4. Increases projectile penetration by 80%.
   
   
5. Increases projectile damage by 20%.
   Increases projectile penetration by 60%.
   
   
6. Increases shot number by 2.
   Switches shot spread to angular.
   
   
7. Increases shot number by 4.
   Increases projectile damage by 80%.
   Increases knockback by 50%.
   Increases ammo by 50%.

1. Increases fire rate by 20%.
   
   
2. Increases reload speed by 45%.
   
   
3. Increases fire rate by 40%.
   Increases reload speed by 25%.
   
   
4. Increases fire rate by 10%.
   Increases reload speed by 60%.
   
   
5. Increases fire rate by 30%.
   Increases reload speed by 50%.
   
   
6. After reloading, you have a 30% chance of increasing your fire rate by 200% until your next reload.
   
   
7. Increases fire rate by 300% based on how low your current ammo is.

1. Increases critical chance by 10%.
   
   
2. Increases critical chance by 10%.
   Increases fire rate by 15%.
   
   
3. Increases critical chance by 15%.
   Increases critical damage by 15%.
   
   
4. Increases critical chance by 15%.
   Increases critical damage by 25%.
   
   
5. Whenever a shot kills an enemy with a critical hit, it increases your next attack's shot number by 1.
   
   
6. Increases critical chance by 20%.
   Surplus critical chance turns into critical damage.
   
   
7. Hitting a critical shot empowers your next attack with 60% increased critical damage.

1. Increases ammo by 30%.
   
   
2. Increases ammo by 50%.
   
   
3. Increases ammo by 20%.
   Increases projectile damage by 20%.
   Increases fire rate by 20%.
   
   
4. Increases ammo by 100%.
   
   
5. Increases ammo by 50%.
   Increases projectile damage by 200% of your ammo.
   
   
6. Increases shot number by 1.
   
   
7. Every attack consumes only 1 ammo.

1. Gives you 0.5 extra hearts.
   
   
2. Gives you 1.0 extra hearts.
   
   
3. Gives you 1.5 extra hearts.
   
   
4. Increases projectile damage and fire rate by 10% based on your health.
   
   
5. Every 200th enemy killed heals you by 0.5 hearts.
   For every heal, your next heal needs 200 more enemies killed.

1. Increases movement speed by 20%.
   
   
2. Increases movement speed by 10%.
   Increases dodge chance by 10%.
   
   
3. Increases movement speed by 15%.
   Increases dodge chance by 15%.
   
   
4. Increases invulnerability time by 200%
   Increases knockback to enemies when damaged by 100%.
   
   
5. When invulnerable, you gain the following bonuses:
   Projectile damage +200%.
   Fire rate +150%.
   Critical chance +100%.
   Reload speed +100%.

1. Your shots have 35% chance of inflicting poison.
   
   
2. Your poison chance is increased by 20%.
   Your poison damage is increased by 50%.
   
   
3. Your poison chance is increased by 25%.
   Your poison duration is increased by 100%.
   
   
4. Poisoned enemies are 35% slower.
   
   
5. Your poison speed is increased by 40%.
   
   
6. Your poison damage is increased by 50%.
   Your poison speed is increased by 60%.
   
   
7. Whenever an enemy is killed by poison, enemies nearby are inflicted with poison.

1. Your shots have 40% chance of inflicting curse.
   
   
2. Your curse speed is increased by 50%.
   
   
3. Whenever you take damage or dodge, you inflict curse on all enemies nearby.
   
   
4. Your curse chance is increased by 10%.
   Your curse speed is increased by 40%.
   
   
5. Enemies inflicted with curse take 50% more damage.
   
   
6. Your curse chance is increased by 10%.
   Your curse speed is increased by 60%.
   
   
7. Whenever you kill a cursed enemy, they explode dealing curse damage in an area of effect.

1. Whenever your shots hit an enemy, you have 40% chance of summoning a lightning.
   
   
2. Your lightning chance is increased by 15%.
   Your lightning damage is increased by 40%.
   
   
3. Your lightning chance is increased by 20%.
   Your lightning damage is increased by 80%.
   
   
4. Your lightnings can also deal critical damage.
   
   
5. Your lightnings target the closest enemies.
   
   
6. Your lightning chance is increased by 10%.
   Your lightning damage is increased by 150%.
   
   
7. Your lightnings deal damage in an area of effect.

1. Now and every 5 waves you summon a star ally that also shoots projectiles.
   
   
2. Your star shots have 40% increased damage.
   
   
3. Your star allies have 70% increased fire rate.
   Your star allies can also deal critical damage.
   
   
4. Your star shots have 100% increased damage.
   
   
5. Your star shots deal damage in an area of effect.
   
   
6. Your star shots have 130% increased damage.
   Your star allies have 80% increased fire rate.
   
   
7. Your star shots have 9999% increased projectile penetration.

1. Whenever you shoot, you have 40% chance of summoning an arrow projectile.
   
   
2. Your arrow chance is increased by 15%.
   Your arrows have 30% increased damage.
   
   
3. Your arrows can also deal critical damage.
   
   
4. Your arrow chance is increased by 15%.
   Your arrows have 70% increased damage.
   
   
5. Enemies killed trigger your chance of summoning arrows.
   
   
6. Your arrows summon 2 other arrows upon impact.
   
   
7. You summon twice as many arrows.

Rare Upgrades

• Increases the amount of cheese that enemies drop by 50%.

• Increases your projectile penetration by 100%.

• Increases dodge chance by 25%.

• Increases all damage sources by 100%.

• Heals your health to full and gives you 1.0 extra hearts.

You need to be at 2 or less hearts for this upgrade to appear.

• Increases projectile damage by 250% for 5 waves.

• Increases fire rate by 250% for 5 waves.

• You have infinite ammo for 5 waves.

1. Non-existent.
   
   
2. Increases your weapon's base ammo by 4.
   
   
3. Increases your weapon's base damage by 2.
   
   
4. Increases shot number by 1.
   
   
5. Increases shot number by 1.
   Increases your weapon's base damage by 2.
   Increases your weapon's base ammo by 4.

Cursed Upgrades

• Your total amount of hearts are reduced to 1.0.
  
• Your total bonus projectile damage is multiplied by 2.0.

• Your critical damage is always at 300%.

• All your bonus movement speed is transformed into critical chance.

• Decreases your total ammo by 99%.
  
• Increases your projectile penetration by 9877%.
  
• Increases projectile damage by 250%.

• Your reload time takes 2.0 times longer.
  
• Your number of shots is 3.0 times bigger.

Combinations

Now finally, we got to the things you're probably missing, the combinations, combinations can only be acquired when two specific upgrades are maxed out, with the exception of the last combination on this list. The combinations names already make it pretty obvious but the combos will be listed down below anyway.

• Your arrows can also summon lightning.

Lightning VII + Arrow VII

• Your arrows can also inflict poison.

Poison VII + Arrow VII

• Your arrows can also inflict curse.

Curse VII + Arrow VII

• Your star allies can also summon arrows.

Star Ally VII + Arrow VII

• Your lightnings can also inflict poison.

Lightning VII + Poison VII

• Your lightnings can also inflict curse.

Lightning VII + Curse VII

• Your star allies can also summon lightning.

Lightning VII + Star Ally VII

• Your star allies can also inflict poison.

Poison VII + Star Ally VII

• Your star allies can also inflict curse.

Curse VII + Star Ally VII

• Your debuff damage is increased by 100%.
  
• Your debuff speed is increased by 100%.

Curse VII + Poison VII

• Your temporary upgrades will last through all waves.

Requires getting all 3 temporary (T) rare upgrades in the same run, (Impact T X, Rush T X and Ammo T X) if you're having trouble with this one, going the rare upgrades path with Mr. Lucky and equipping the extra rare chance global upgrade should help you a lot.

Cheese Moon
Get all achievements available