Weird West: Definitive Edition

This too can be done in Grackle. Climb onto the roof of a building, such as the Gun Store and walk/jump off when an NPC is walking underneath. If you manage to land directly on them they should be knocked unconscious and the achievement will pop. See my video for more detail:

This also works on animals, such as the horses tethered to the posts.

I managed to get this by falling on a either a body or unconscious enemy from a roof in Greenwood Run, this is were you will free the blacksmith and find more info on your husband.

Greenwood Run is a story related area and is one of the first few places you go to.

You can probably get this anywhere where you can fall from high enough, probably even Grackle.

Edit: So it turns out that falling on any NPC will trigger the achievement. Others have said they got it through a pig and a horse.

Similar achievements may also be glitchy but in a good way.

No need for falling from higher ground

Just stand next to a npc and jump on their heads from ground level. It might take a few little jumps to knock them out.