There are no missable achievements so take your time and enjoy the game. At certain points the game will flag a 'point of no return' through dialogue but you don't have to worry about it will not in any way hinder you from obtaining 100% in one playthrough.

Tips for new players looking to 100% the game:

• Don't upgrade your equipment until the end game - you'll find better gear anyway. Spend your money on upgrading spells. End-game quests and dungeons have way more gold than you can save early on anyway, so upgrading gear later will be easier.
  
• Use the Cat Solder or Dog Soldier Set as they provide 20% extra experience from pickups (which means everything except quest rewards). The items have decent stats and if you keep one character equipped with them for most of the game you won't have to do any XP farming later on.
  
• If you're playing single player, it seems the AI companion cannot take damage. Just make the AI a full glass-cannon who will shred through enemies (preferably with magic damage).
  
• Some spells, like Furry Shield and Purrserk don't benefit from extra Spell Power. If you are running a warrior/mage combo (which you should) you can put these spells on your warrior without any downsides.
  
• Unlike Cat Quest 1, the slow effect on Freezepaw is set at 50% and does not scale with levels. It's not worth upgrading the spell past Level 3 as the cost gets high and the damage scaling isn't that great.

These are obtained as you progress through the main storyline.

Complete the tutorial quest. Triggers when you reach Felingrad.

Triggers when you enter the Lupus Empire as part of Main Quest 07 - The First Kings.

There are 4 Royal Arts which you will unlock as you progress through the main quests.

• Pawer Rolling - Roll through enemies to do damage!
  
• Pawer Smash - Attack during a roll to Pawer Smash!
  
• Water Walking - You can walk on water!
  
• Full Royal - Critical hits now summon a royal blast!

You will receive this achievement at the end of the side quest Pawt Bay Lighthouse - III - Gift of Water Walking. This is a requirement in order to reach Main Quest 13 - Trial of the First Kings.

Complete all 21 main quests.
This great spreadsheet[docs.google.com] contains a list of all the main quests including Base Level and Location. For more information on each Main Quest, see the Fandom Wiki[catquest2.fandom.com].

These achievements will require a bit more work. They're in the order you're likely to unlock during your playthrough.

If you use the Cat Soldier and/or Dog Soldier equipment (Experience pickups +20%) throughout the game you should reach level 99 (or very close) by the time you finish most of the side quests.

There are 12 spells to be found in Cat Quest II by interacting with Ancient Tablets. Information is from the Fandom Wiki. Note that each time a new spell is unlocked the maximum mana of each character is increased by 2.

• Flamepurr[catquest2.fandom.com]
  
  • Flavour text: Sets your enemies on fire!
    
  • Location: Brave Cave[catquest2.fandom.com]
• Freezepaw[catquest2.fandom.com]
  
  • Flavour text: Freezes and slows your enemies!
    
  • Location: Brave Cave[catquest2.fandom.com]
• Healpaw[catquest2.fandom.com]
  
  • Flavour text: Replenishes health of allies!
    
  • Location: Near King Sigil Ruins[catquest2.fandom.com] during Main Quest 04 - The Purrsecutor
• Astropaw [catquest2.fandom.com]
  
  • Flavour text: Shoots lasers from space!
    
  • Location: Northwest of The Long Road
• Lightnyan[catquest2.fandom.com]
  
  • Flavour text: Zaps enemies with lightning!
    
  • Location: West of Wall of Lupus
• Cattrap[catquest2.fandom.com]
  
  • Flavour text: Lays a trap for your enemies!
    
  • Location: west of Drakoth's Vault (North West of the map, requires Water Walking)
• Manapaw [catquest2.fandom.com]
  
  • Flavour text: Replenishes mana!
    
  • Location: Near Excavation Site, East of The Banished (skull)
• Furry Shield[catquest2.fandom.com]
  
  • Flavour text: Creates a shield to reduce damage!
    
  • Location: Cave Grotto[catquest2.fandom.com]
• Purrzerk[catquest2.fandom.com]
  
  • Flavour text: Increases attack!
    
  • Location: Whisk Cove[catquest2.fandom.com]
• ForceWoofer[catquest2.fandom.com]
  
  • Flavour text: Unleashes a spinning tornado!
    
  • Location: Far-Fetched Cave[catquest2.fandom.com]
• Gravi-ruff[catquest2.fandom.com]
  
  • Flavour text: Sucks enemies into a black hole!
    
  • Location: Tomb of the Follower[catquest2.fandom.com]
• Celestail[catquest2.fandom.com]
  
  • Flavour text: Unleashes a giant beam from space!
    
  • Location: Cactus Cave[catquest2.fandom.com]

Complete all 67 side quests!
This great spreadsheet[docs.google.com] contains a list of all the side quests including Base Level and Location. For more information on each Side Quest, see the Fandom Wiki[catquest2.fandom.com].

Clean up the underground! A dungeon is marked as 'Complete' when you have killed all the enemies and opened every chest in the dungeon. Note that if you've missed a chest and left the dungeon, in order to 'Complete' it you only need to open the remaining chest - no need to kill all the monsters again.

A full list of dungeons sorted by Area can be found on the Fandom Wiki[catquest2.fandom.com].

If you've been playing the game normally and trying to clear everything without checking a guide, you've likely remained stuck at 70/73. The remaining dungeons are likely:

• Cave of the Lion[catquest2.fandom.com] [Level 150] - unlocks after completing the main quests
  
• Tomb of the Wolf[catquest2.fandom.com] [Level 150] - unlocks after completing the main quests
  
• Lonely Cave[catquest2.fandom.com] [Level 200] - contains the highest level enemy in the game

Note 23/04/2024: It seems a few more dungeons have been added to the game. Based on comments left on this guide, it seems you only need to complete any 73 dungeons, not necessarily the specific 73 that were initially present.

Collect all 101 items!
This great spreadsheet[docs.google.com] contains a list of all the items sorted by Type and Set. For more information including effects and drop locations see the Fandom Wiki[catquest2.fandom.com].

If you've been playing the game normally and trying to clear everything without checking a guide, you've likely remained stuck at 92/101. This is likely due to you having not cleared the three end-game dungeons listed in the Dungeon Master section.

Note 23/04/2024: It seems a few more items have been added to the game. Based on comments left on this guide, it seems you only need to acquire any 101 items, not necessarily the specific 101 that were initially present.

Thank you to nicaragua for making the logo. I am worthless in PhotoShop.

Cat Quest 2's Fandom Wiki[catquest2.fandom.com] was a great source of information for this guide.

Reddit user u/bravetoaster compiled a great spreadsheet[docs.google.com] with all of the items and quests in the game. All of the quest and item information in this guide is based on it.