It crashed upon opening the terrain editor in-game 
I saw the tetris logo for like, 1 second 

So why the terrains you uploaded don't have the "SOIL" file like other WA terrain ?

Error log uploaded

Making custom terrains

Download:
http://worms2d.info/WA_directory_editor

The program has a lot of bugs so good luck.

Open an existing Level.dir file and click "Extract, convert, log" and select a folder.
All the img files and spr files will be converted to img.bmp and spr.bmp.

Inf files: There is one for each map object, and they specify where on the map they can be placed (on the grass, hanging from ceiling, sides)
Spd files: There is one for each spr file (animated sprites), open with text editor. They're self explanatory.
index.txt: Just lists all the objects.
Level.dir.txt: is the log file that sprite editor uses when you click the "Reconstruct from log" button.

All bmp files should use a 113 colour palette (including black).
When creating/editing bmp files, you should save them as 8 bit OS/2, and make sure black is indexed 1 (I only know how to do this in Photoshop)
After you've created your bmps and written your spds and infs.. make sure the img, spr and inf files are listed in level.dir.txt, then use sprite editor to reconstruct from log, and save the DIR file.

The process is a bit of a headache but doable. Any problems feel free to message me.
If you want to try something else to generate your own terrains: http://worms2d.info/MapGEN

It did not work on non steam WA 3.6 
Guess I'll try to replace some current terrain

I was playing with PX, used Earth Quake to round up the worms and one Battering Ram to one shot them all, after the explosion ( which knock 16 or so worms off the map ) the replay system kicks in and then it crash, has to open task manager to kill it 
What exactly caused it ? I've made as much as 21 kills before and there's no replay ( maybe because the damage ? idk... )

As Rick already said, there's infinite amount of possibility, it's better to just not think about it 

I have dropped a worm from 3000 pixels and get 85 HP of FD. No ts it was. I guess since max speed is reached, the FD will be maximum possible and doesnt matter how much have you travelled, 400, 1000, 3000 or 30000 or whatever.

  SCIENCE !

57 people vote that they want it to come back, but so far, only 12 have voted.
Kind of a disparity there, guys!

https://www.tus-wa.com/awards/

The problems is obviously not everyone know what to fill in and there's too many boxes

I have tried to keep myself calm after my first ban by MonkeyIsland, but GeneralEcchi has driven me nuts. I would thank you for muting him. But, by the way, is anyone going to play Epic Battle Fantasy 5 Battle Demo. It is so great, just like your favourite Ye Olde Armageddon. And the complete game will be great too.

I actually have to thank him for muting me because that gave me a new signature lol

It's like emotions, if you never feel sad before you can never know what happy is like 
So yea, I'm okay with shitty game being made