The bombard cannons are too strong.
They are good against:
- infantry units
- somehow elephants
- every siege units
- buildings and walls
- for some obscure reason, fishing ships
Basically, they are a better ram with greater range and huge mobility, lacking pierce defense but can be defended better and better trebuchet at mobility and accuracy. The great bonus is mobility and that even trebuchet is countered by bombard cannons but the trebuchet itself doesn’t counter anything. Another thing is that it can be created without a castle. So, you don’t have to invest stone, making it cheaper than a trebuchet, even considering chemistry.
Lets see how can you defend against them:
Premises is that the knight line doesn’t have any bonus against them so, while it isn’t useless and pretty good due to cavs mobility, halbs can defend the cannons pretty easily, given cannons range.
- eagle warriors that can be defeated by any gunpowder unit such as hand cannoneer or the militia line except mayans eagle warriors
- mangudai that are the most effective due to their mobility and high fire rate but are available only for 1 civ
- rams but easily defendable as rams are slow and can even be countered by the spear line
- condottiero but only italians and co. have it
- petards that will never reach them
- magyar hussars that are available to 1 civ and can be easily defended with halbs with the box formation
- bombard cannons
and that’s it. Because of their range and mobility all the threats are easily cancelled, except for mangudai that can only be used by 1 civ and themselves.
So my proposal is to nerf them with 2 range, making them 10 range unit (min range reduced to 4), thus vulnerable to castles that are upgraded but still quite good against the other things I listed but more vulnerable given its range. To balance this, give them +2 with siege engineers and +1 pierce armor or better, make a separate tech that cost 500 wood and 300 gold and give them those bonus.
My other proposals are to remove them completely from the game or put back the tech that needed to be researched for them with increase cost of gold by 50.