Here is the full list of all 15 Time Splatter achievements.
See the Game Over Screen for the First Time
Exit the Dungeon
Kill 50 Plagued
Pick 30 Ammo Crates
Kill 50 Knights
Kill a Dinosaur
Pick 10 Ammo Crates
Kill 50 Enemies
Kill 10 Knights
Kill 30 Plagued
Kill 30 Enemies
Kill 1 Knight
Kill 10 Enemies
Pick an Ammo Crate
Kill 1 Plagued