Here is the full list of all 28 Tallowmere achievements.
Make it to Room 60 without sacrificing any kittens.
Make it to Room 50 without sacrificing any kittens.
Acquire a 6-star piece of headgear without sacrificing any kittens.
Make it to Room 40 without sacrificing any kittens.
Acquire a 7-star piece of headgear without sacrificing any kittens.
Acquire a 7-star shield without sacrificing any kittens.
Kill yourself using your own grenades.
Acquire a 7-star weapon without sacrificing any kittens.
Acquire a 7-star outfit without sacrificing any kittens.
Acquire a 5-star shield without sacrificing any kittens.
Acquire a 5-star outfit without sacrificing any kittens.
Acquire a 6-star outfit without sacrificing any kittens.
Acquire a 5-star piece of headgear without sacrificing any kittens.
Make it to Room 30 without sacrificing any kittens.
Acquire a 6-star shield without sacrificing any kittens.
Defeat Jazza without sacrificing any kittens.
Sacrifice all nine kittens and die a little inside.
Receive healing from Lady Tallowmere while on 1 health.
Acquire a 5-star weapon without sacrificing any kittens.
Acquire a 6-star weapon without sacrificing any kittens.
Return the flag without dropping it, and without sacrificing any kittens.
Make it to Room 20 without sacrificing any kittens.
Defeat the three-headed Hydra without sacrificing any kittens.
Return the cursed flag to Lady Tallowmere without sacrificing any kittens.
Make it to Room 10 without sacrificing any kittens.
Free Lady T from her peril without sacrificing any kittens.
Blow yourself up with a rocket launcher.
While stealthed with the Emerald Dagger, stab an enemy in the back.