Great idea
What should the size of the explosion be?
Only joking
A large circular explosion would be good though. These bombs ought to be more destructive than regular lemming-Bombers, particularly if they require remote detonation.
Should it be harmful to lemmings nearby?
No, but it
could trigger them to all transition to Jumper spontaneously. Serious idea
Should a different name instead of "bomb" be considered to avoid confusion with the Bomber skill? Perhaps "dynamite"?
Yes, "Dynamite" is a good idea.
Should they be able to remove steel?
No, steel should always be indestructable.
Huh. You picture this differently from how I was picturing it. I thought the bombs would be inside specialised terrain blocks (which would be indestructible by other means), and detonating them would destroy those terrain blocks and nothing else.
Strongly against this idea, unless you want NeoLemmix to become more and more like the mobile game
NeoLemmix is, ultimately, a pixel-level game, with many tools incorporated to facilitate this level of detail and design.
It seems a shame to limit the idea to only affecting certain-sized pre-placed blocks, rather than being able to place the object potentially anywhere in a level and have it affect multiple different pieces of terrain in any direction - this would be a far more useful and interesting way to implement it.
EDIT: Having said that,
Proxima's idea could be re-interpreted as a "vanishing blocks" or "opening multiple doors" idea, which - to be fair - is equally interesting, but (to my mind) ultimately a different idea.