Factorio Forums

The Tank cannon shell piercing works in a pretty weird way. Here's how it works:

The shell deals 300 damage, and his 300 piercing power. When it *kills* a target, if the inflicted damage is less than or equal to the piercing power it pierces and hits a second target for up to full damage, the piercing power is reduced by the amount of damage inflicted, if it's still over 0 it can piece again, and again hit for up to full damage.

So if the Tank is aimed at two targets with 300 hitpoints, it will destroy both of them and deal 600 damage.

But if the target has 301 hitpoints it will not pierce, so it deals only 300 damage.

This results in some weird stuff. Like when killing spawners, the first shot will leave the spawner with about 80 hitpoints, the second shot can pierce through that spawner and hit another spawner behind it for full damage, so you can "chain" spawner kills in this way, getting a full kill per cannon shell if you line up the shots right.

Piercing Power isn't increased by the damage upgrades. Once you get +40% damage the shell will always 1-shot spawners, but it never pierces unless the spawner was damaged to below 300 hitpoints, in that case it can eliminate the injured spawner and kill a healthy spawner behind the injured spawner.

Suggestion

The piercing power should be how much damage the cannon shell can inflict - in effect, the cannon shell's momentum. So a Cannon Shell might have a damage of 300 and a piercing power of 600, if it hits a target with 350 hitpoints, it takes off 300 hitpoints, pierces through leaving the target with 50 hitpoints and can hit another target. If the next target has 250 hitpoints it outright kills that target and keeps going, and can inflict 50 damage on a third target - the leftover piercing power. Or the piercing power could just be the same as the damage, which means the cannon shell is absorbed when it hits a big target, but when it hits a bunch of smaller targets it can kill several of them, but the total damage inflicted won't add up to more than the shell's damage. That is a cannon shell which says it inflicts 300 damage, will inflict 300 damage regardless of the size of the targets it hits/pierces, if the targets have 250 hitpoints, it'll kill one and hit a second for 50 damage, and will not kill two for 500 damage.

Coming up with sensible piercing projectile behaviour can be hard. Intuitively, one expects it to have the following behaviours:

-Piercing ammo should go through enemies it kills
-Piercing ammo can sometimes go through enemies that aren't killed by it.
-Piercing ammo should be stopped dead in its tracks by a really tough enemy.
-A projectile that has already gone through one enemy should now be weaker, preferentially in proportion to how tough the enemy was that it just went through.

An easy way of doing this within the game's mechanics would be to deduct the resistances of the enemy from the projectile damage every time it hits an enemy. So for instance with 4 behemoth biters lined up (with 8/20% physical resist) a 300 damage shell would lose 20% followed by 8 damage with each biter it went through. This would look like: 300 --> 232 --> 177.6 --> 134.1 --> 99.3 The shell would stop completely once the damage value becomes negative.

Intuitively, a 300 damage tank shell shouldn't be passing through a 5000 hp behemoth biter at all. The hp and resistances of each enemy would have to be altered to account for this (where hp is drastically lowered and resistances drastically increased to create more realistic penetration behaviour where a shell doesn't just cut through everything, doing marginally less damage each time).

Of course this doesn't account for penetrating power as a game concept. We want some projectiles to penetrate better than others while doing the same up-front damage.

Perhaps to modify your idea - the penetrating power is the percentage of health a projectile can remove and still penetrate through. In this case, a smaller percentage is better. If the penetrating power is 50%, then a round reducing an enemy to half health or less will pass through, perhaps with reduced damage as per the enemy's resistances as I suggested above.

A third possible system: The projectile damage gets reduced per enemy it goes through as above, but the penetrating power reduces the reduction in damage, if you follow me. A normal 300 damage shell with a 100% damage reduction modifier hits a behemoth biter and loses (0.2*300 +8) = 68 damage on its way through. A penetrating shell with, say, a 50% damage reduction modifier halves the amount of damage lost, so (0.2*300+8)*0.5=34 damage is lost on its way through and the projectile can pass through many more biters before running out of damage.

When I was thinking more, the piercing shell basically represents an anti-tank shell.

The way these work is they punch through the armor of a target and explode inside it into a spray of shrapnel and high velocity molten metal, (ideally) that metal gets caught inside by the armor on the far side and bounces around shredding everything. But if the target is inadequately armored the shrapnel can just punch out the far side and carry on, which significantly reduces the lethality of the shell.

The real problem then, is not that the round can "dud" on spawners, but that it can dud on Behemoths. There should be some hitpoint threshold (perhaps twice the piercing damage) that causes the shell to inflict both the piercing damage and the physical/explosion damage to the beefy target it hits.

So there would be 3 possibilities:

• Against particularly weak target, the shell doesn't even get "triggered", it just makes a hole (deals piercing damage) and keeps going and can still be triggered.
• Against moderately large targets, the shell does get triggered, but doesn't inflict its full damage because the shrapnel leaves the far side.
• Against very large target, the shell gets triggered and inflicts both piercing and physical/explosion damage.

A good option to choose from here would be how Armor Piercing shells work in games like Armored Warfare and World of Warships. The AP shell needs to penetrate a certain amount of armor, or in this game, deal a certain amount of damage before it explodes. The shell should have two damage values, like it already does, one for arming and one for detonation. The shell needs to deal the full amount of arming damage to an enemy or group of enemies before it will detonate. If the total arming damage is not met by hitting one enemy it passes through to the next and so on until it hits something like a tree or rock or falls into the ground.

Now there is a choice when it comes to researching. Should we increase both the arming and detonation damage? Should we only increase the detonation damage? We could also lower the arming damage and increase the detonation damage.

I am inclined to increase both the arming damage and detonation damage. It isn't very easy to swap ammo in this game which makes reacting to combat conditions harder. Keeping the AP shells loaded for taking out the really big biters or spawners and using the machine gun and now flamethrower for the smaller clumped up threats seems fairly reasonable.

If they ever made a good combat revamp I would love to see some unique uses for the AP, Explosive, and Uranium rounds.