These are some suggestions that I feel would make the game more fun for the people who like the more explosive aspect of life.
1.Siege engines can be linked to mechanisims so you can create batteries of catapults that fire upon pulling of a lever or other examples.
2.Explosives. Use the Alchemy labour in other to produce. Some need gunpowder or other exotic materials- gunpowder needs 1 charcoal, one saltpetre and one sulphur to produce. Different types have different types of blast area, all do some damage, force all units in blast area back and have a chance to set them on fire.(force output etermines speed at which affected units are forced back. damage is blunt and burns due to fire, shrapnel and shockwave.)
All can be manually detonated by assigning to lever or pressure plate.
Type ideas- Booze bomb-needs any alcohol. low force output, damage and blast area-1 tile?- but high fire chance due to burning booze.
Mining charge-needs 1 gunpowder and one wooden barrel. 2 tile blast radius, destroys all non-fireproof stones in area. loiw damage but high force.
Demo charge- magma-proof barrel, 3 gunpowder, 1 primer agent. destroys all stone within 3 tiles when detonated. useful for a last ditch attempt to destroy an invading army or as a self-destruct or mining rooms. high damage, force and 100% fire chance.
3-all explosives can be fired from catapults but have a chance to explode on launch depending on quality of explosive, catapult and operator skill.