First, I’m on my phone ATM so no terrible mockups. Yet.
Fighters are a bit of a problem (largely due to limited AA weapons that don’t suck and laser cannon having too much AP) and I think there are some solutions that are more interesting than nerfing etc.
Firstly, multiple gun turrets. This has many applications, but if frigates could mount quad-laser cannon turrets, they’d actually have guns that could hit fighters AND nit be outgunned by a single squad. Nerd the tracking a bit, make it heavier than 4x laser cannon etc, but using multiple ‘lower tier’ weapons on larger ships could mitigate issues with tracking.
Also, different kinds of shields. The laser is overpowered because of the cool way fighters in close bypass shields. That’s awesome, frankly, but it could be made more interesting. Some shields are way too big which hurts those ships, so better sized circles would help statistically. Also, different kinds of shield envelopes (oval, form fitting, etc) would allow a tradeoff between ‘strength’ and ‘vulnerability to fighters’.
I’d like to see interesting shields too. An idea in this direction would be ‘slow shields’ that slow down ships within the envelope. Base thevreduction on mass and it’ll only really affect fighters, and allow ships a better chance to hit strafing fighters. Given the overlap, defence ships could assist nearby ships under attack with shields less suited for ‘normal’ combat.
I love the idea of different types of sheilds. It would be really cool to have the other shapes on more “advanced” shields.
I like where you’re going with this. The idea of an anti-fighter weapon has been passed around a lot. There seems to be a general consensus that something like a flak cannon (very low damage (and DPS), but good accuracy against fighters, whether through tracking speed or AoE) would do wonders. I think your multiple gun turret would also work: a single turret that could shoot multiple ships at once would stand a better chance against a swarm of fighters. I don’t think tracking speeds and weight would even be the issue, you basically just want to make it good against fighters and not much else. Give it a really short range (the uber-dangerous laser fighters have a max range of 300 and less than that is needed to get under shields) and make armor and shield penetration negligible and it should be useless against anything but a fighter.
I think an alternative is to revisit the hit calculation. Hit chance is (1-(ship speed / tracking speed))*(0.5 + (ship size / 256)*0.5). (I hope that’s legible; that’s a lot of brackets.) Even against the fastest turret (cruiser defense laser), an average fighter (2.4 speed, 12m long) will only (theoretically) be hit 27.3% of the time. I just did a test with a 2.38 speed Federation Leopard build against a cruiser with 7 defense lasers and the actual hit rate was more like 13%. I’m also not sure what units the fire interval are in, but the 550 interval cruiser defense lasers took about 1.4s between shots. At that rate, it took 51s to take out half of the 16 ship swarm (20 HP each). A quick calculation puts that at 90 seconds to kill them all (some of the remaining fighters were probably partially damaged). I’ve seen fighters rip a cruiser to shreds in half that time.
Maybe we should change the hit calculation so that size or ship speed doesn’t have as much of an effect. It seems silly that tracking speed should have to be several times larger than ship speed just to get near guaranteeing a hit. It also seems strange that anti-fighter weapons would still be capped at about a 52% chance of hitting, just because of the size of the ship.
Still, there are lots of options for weapons. We could make a weapon like like an EMP blast that would trigger when the fighters get close to the cruiser. This would disable them temporarily, preventing them from doing damage and leaving them mostly immobile. If the timing is balanced well (maybe only fire once every 30 seconds?), this could give the cruisers a chance to decimate the fighters while still giving the fighters a chance to do some serious damage. Perhaps, as a repercussion, the cruiser is left without shields for the same time that the fighters are down. Lowering your shields to avoid being demolished by fighters would be quite a trade off, don’t you think?
Stupidly-fast tracking weapons (like the new and improved anti-fighter missiles), shorter fire intervals, multiple shots – there are lots of things we could do to tweak the numbers within the existing formula. The hardest part is making sure it doesn’t make a weapon that’s also superior against other ships. Again, range, armor and shield penetration, and overall damage are things that could balance this.
Frankly, I’d love to see powerful weapons with little to no armor penetration. That would make armored fighters a viable option.
I think the way to go with flak is to wait for the AoE code Cliffski has mentioned. That’s the way to do it properly, but there are many ways to mitigate fighters while making the game interesting. I really think the AoE ability will help out all over the game.
Apologies for my poor punctuation etc in the OP, btw. Bloody phones. 
Anyway, the multiple weapon turret is my solution to a few problems. At the moment pretty much zero guns on frigates can hit a fighter with any regularity (thanks for the maths on that, btw) but massed fighter guns do fine. Thus, allowing larger ships to mount smaller weapons in multiple-turrets seems like a good idea, especially given it’s ‘characterful’ in that it means you now have a frigate armed with 16 guns totally useless against anything with a shield (and after a nerf, anything with decent armour). This can be taken further, by creating ‘dual beam turrets’ that are heavier and draw more power and crew inefficient, but allow you to pack more DPS onto a hull. Ultimately I’d like to see the tiered module system disappear and have it be ‘naturally’ impossible for a fighter to mount frigate guns (outside of crazy bomber designs) instead of simply being unable to choose them. I mention reducing tracking speeds and increasing weight simply for balance reasons; you don’t want to make anything TOO good vs fighters, you always want it to be a tradeoff to keep the game interesting. I really like fighters (they’re very visually interesting which is a big draw for the game) they’re just totally breaking the game right now, and you can fix that AND make the game more interesting at the same time.
With regard to shields, while I imagine it’d create a bit of work for Cliffski, the idea of tradeoffs between ‘stablity’ and ‘shield hp’ and ‘coverage’ and ‘exposure’ would allow many types of shields to be good for different things. My ‘ablative frigates’ want the biggest shield they can get to catch as much incoming fire on other ships as possible, and if Cliffski declared ‘closer to circular = better shield mitigation’ or similar, those ships would have good shields per weight. For combat cruisers, you might want to accept ‘weaker’ shields or more easily penetrated shields in exchange for reducing it’s size and reducing hit chances.
The idea of a local area-attack against shields is one I’d thought of - ‘attack shields’ - but hadn’t considered treating it as a weapon. Shields that gave damage as fighters entered didn’t seem practical (bumpercars is not a tactic), but the ability for a ship to crush fighters within it’s shields by collapsing them is very interesting. No idea how the AI would use this effectively, of course!
It would be good if you could buy point-defense shields, that explicitly shield a single module (eg the armor module), and slowly recharges.