"Build fifteen different traps on one map". That means you have to unlock almost all of the traps and then build one of each on a single map. There are only a couple of maps where this is possible.

Thanks for the response datguy13. I'm also having a problem getting this achievement. Nevermind 15, I've build all 25 traps on one map (map VII), beat it and it still didn't unlock. It's got to be bugged. Any other suggestions are very welcome, thank you.

I've tried to build 15-25 different traps in a single map. I've tried to not get any kills myself and let the traps kill them all. It still doesn't unlock for me. It does not pop up after building 15 different traps when you have build them and neither does it pop up when you finish a map.

We are not alone:

https://forum.neocoregames.com/index.php?/topic/38777-achievements-no-pasaran-killing-floor-not-progressing/

I've left a message there as well. Hedrox Neo, add me if you want to try for the co-op achievements sometime.

I don't know what might be wrong. I managed to get the achievement under normal play conditions, and it's highly unlikely that a later patch would break an achievement condition link.

Doesn't work for me either. Any news since? The link posted by @Dale is dead... Any hints?

Hi SourceSeeker. I've included a link to another discussion. You used to be able to download an old version of Deathtrap via the Steam console and the achievements worked. You can no longer do this via Steam but if you see the answer below my first post, Larkin has included instructions on how to do it via another website. Good luck.

https://steamhost.cn/steamcommunity_com/app/310510/discussions/0/1692659769954607561/