I just used a "spawn block action" - steel, under the existing terrain.

And adjust it to spawn upon level start ?

Originally posted by DD-Indeed:

And adjust it to spawn upon level start ?

yeah

Okay, thanks !

EDIT: I managed to do that, but only 1 block was spawned. What type of trigger I need to use, so it selects dragged area ?

you cant, you have to create multiple actions in the trigger. One for each block.

Tbh... dont ♥♥♥♥♥♥♥ use them. Steel blocks should only be used if you messed up your design in the first place and HAVE TO have them.

edit:
I still gotta finish the new version of my tool, it will contain functionality to spawn multiple blocks, and maybe the steel layer thingy in two variants (depending on relevance to performance)
Feel free to check out my guide and/or subscirbe to the corresponding thread for updates on it :)

Gonna do that, sounds great.

Nah, ain't got no patience to put hundreds of ''hidden'' blocks one by one. Luckily, those ain't a ''must be''-things in the level desing, it's just that they would have made the levels easier in some places. But you can always try again, if you screw it up badly and can't progress, learn from mistake. :) Difficulty level isn't in the Teletubbies-section.

One important design method is the use of ladders and ziplines to ensure the level is always possible to complete while maintaining a natural look.

Absolutely. Nothing isn't as frustrating, than a level, where is not possible to progress, if there's been lots of explosions in large area and no ground anymore, and no ziplines/ladders to help you out.