Here is the full list of all 75 Circa Infinity achievements.
Complete Part II
Complete Every Level in Part I without Dying
Unlock 12 Color Palettes in Circle Affinity
Reach the 10th Circle of Part II in Circle Affinity
Reach the 25th Circle of Part I in Circle Affinity
Complete Part I
Complete any level in Part I by only moving in one direction without stopping
Complete any level in Part I by only moving in one direction
Reach the 10th Circle of Part I in Circle Affinity
Complete Part III
Complete Part IV
Complete Part V
Complete Every Level in Part II without Dying
Complete Every Level in Part III without Dying
Complete Every Level in Part IV without Dying
Complete Every Level in Part V without Dying
Complete Every Level Without Dying
Complete a Speedrun of the game in under 2 hours
Complete Any Level in Part I in under 20 seconds
Complete Any Level in Part II in under 30 seconds
Complete Any Level in Part III in under 40 seconds
Complete Any Level in Part IV in under 50 seconds
Complete Any Level in Part V in under 70 seconds
Have a combined best of under 5 minutes for Part I
Have a combined best of under 6 minutes for Part II
Have a combined best of under 10 minutes for Part III
Have a combined best of under 15 minutes for Part IV
Have a combined best of under 25 minutes for Part V
Run through all of the credits
Complete any level in Part I without moving (jumping is allowed)
Complete any level in Part I without moving or dying (jumping is allowed)
Complete any level in Part III without moving (jumping is allowed)
Complete any level in Part III without moving or dying (jumping is allowed)
Complete any level in Part IV without moving (jumping is allowed)
Complete any level in Part IV without moving or dying (jumping is allowed)
Complete any level in Part I by only moving in one direction without stopping or dying
Complete any level in Part II by only moving in one direction without stopping
Complete any level in Part II by only moving in one direction without stopping or dying
Complete any level in Part III by only moving in one direction without stopping
Complete any level in Part III by only moving in one direction without stopping or dying
Complete any level in Part I by only moving in one direction without dying
Complete any level in Part II by only moving in one direction
Complete any level in Part II by only moving in one direction without dying
Complete any level in Part III by only moving in one direction
Complete any level in Part III by only moving in one direction without dying
Complete any level in Part IV by only moving in one direction
Complete any level in Part IV by only moving in one direction without dying
Complete any level in Part V by only moving in one direction
Complete any level in Part V by only moving in one direction without dying
Have a combined best of under 4 minutes for Part I
Have a combined best of under 5 minutes for Part II
Have a combined best of under 6 minutes for Part III
Have a combined best of under 9 minutes for Part IV
Have a combined best of under 18 minutes for Part V
Complete any level as a devil
Reach the 50th Circle of Part I in Circle Affinity
Reach the 25th Circle of Part II in Circle Affinity
Reach the 50th Circle of Part II in Circle Affinity
Reach the 10th Circle of Part III in Circle Affinity
Reach the 25th Circle of Part III in Circle Affinity
Reach the 50th Circle of Part III in Circle Affinity
Reach the 10th Circle of Part I+ in Circle Affinity
Reach the 25th Circle of Part I+ in Circle Affinity
Reach the 50th Circle of Part I+ in Circle Affinity
Reach the 10th Circle of Part II+ in Circle Affinity
Reach the 25th Circle of Part II+ in Circle Affinity
Reach the 50th Circle of Part II+ in Circle Affinity
Reach the 10th Circle of Part III+ in Circle Affinity
Reach the 25th Circle of Part III+ in Circle Affinity
Reach the 50th Circle of Part III+ in Circle Affinity
Unlock 24 Color Palettes in Circle Affinity
Unlock 36 Color Palettes in Circle Affinity
Unlock 48 Color Palettes in Circle Affinity
Unlock 60 Color Palettes in Circle Affinity
Unlock All Color Palettes in Circle Affinity