short entry: Goblins retain the 1st edition susceptibility to light
from 1st edition, and therefore tend to mostly be active at night or
underground.
Sunlight Sensitivity. While in sunlight, the goblin has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight. They can see in darkness as if it was normal light for them (up to their darkvision range).
Goblins also tinker and create weapons of war, although their creations are usually quite volatile. Firearms are mainly the province of mad goblin alchemists, and are highly suspect in their worth, having the well-earned reputation for being dangerous and unreliable.
Goblins use a rare liquid they call "pyroglycerine" to produce a crystalline dust that they then turn into ammunition for their weapons. Pyroglycerine is highly dangerous and unstable, but the goblins seemingly don’t care. However, even they rarely mass produce pyroglycerine, and transport it even less due to the hazard involved. (Rumors of a goblin war machine that used pyroglycerine as a fuel are totally unsubstantiated.)