Here is the full list of all 17 1 Bit Survivor achievements.
Get an S Rank
Complete the game with no upgrades
Beat the Game as the Hunter Class
Get 50 Knife Kills in a single run
Beat the Game as the Assault Class
Complete the game with 9 or less Heals used
Read the tutorial in less than 5 seconds
Get an A Rank
Roadkill 15 Enemies in a single run
Lose on the 28th Day
Survive Week 4
Beat the Game as the Survivor class
Survive Week 3
Take the easy way out
Survive Week 2
Survive Week 1
Pet Leo in the upgrade menu or main menu