Here is the full list of all 40 I Hate Running Backwards achievements.
Finish a loop without receiving damage with all six curses active
Finish a loop with all six curses active
Finish a loop without receiving damage
Collect 666 souls
Detonate 50 explosive traps
Destroy 30 mines while invulnerable
Kill 10 RoadBulls on the Road ground
Knockback 100 enemies
Finish a game loop
Kill the second form of Ugh Zhan boss
Deflect 500 projectiles
Kill Biomechanoid while four curses are active
Kill 1000 enemies with a hammer
Gather 50k chunks from destruction
Deflect 50 cannonballs
Kill the biomechanoid without being hit
Freeze 100 enemies
Destroy 50 watchtowers
Kill Scrapjack using only the hammer
Destroy a special crystal in the Crystal cave
Get to the Scorpion king using only the hammer
Kill Ugh Zan without taking any damage
Kill Ugh Zan boss
Unlock 15 special weapons
Kill Scorpion King while two curses are active
Kill Biomechanoid boss
Kill the Lava Golem boss
Deflect 20 rockets
Use ultimate ability 5 times in the same run
Gather 5k chunks from destruction
Destroy a secret trash container
Kill the werebull
Heal for 20 health during one session
Kill Scrapjack boss
Kill the Scorpion King boss
Kill the Scorpion King before he burrows
Die
Collect every powerup in one run
Get the combo counter to x50
Destroy weapon crate