Judging from the recent set of postings from people, I suspect quite a few people didn't know about this thread until the recent kickstarter e-mail (myself included). Looking at the date of the original post, I suspect Goldhawk are already a decent way into programming the changes outlined. Despite this, I will add my own comments albeit late. In context of my views, I haven't played the original and have only periodically played the new game so by no means an expert - hence maybe a little bit of a wishlist on my part but... Most of the following is on the assumption that it is still turn based although quite a bit would work in a non-turn based system.
"One of the main things I want to experiment with is to have fewer types of interceptor" - the common idea is to have three types of interceptors consisting of
1) a small, highly manoeuvrable craft that is hard to hit but is limited on the amount of weapons it can carry.
2) a heavy "bomber" that is slower, less manoeuvrable but can carry heavier hitting payloads
3) the "middle of the road" craft.
From a tactical point of view, you may choose a heavy bomber with a couple of the smaller aircraft who do the closing down and acting as a decoy while the heavy aircraft gets into range. This may play out interestingly with "This will allow us to set some combats up as a chase where the UFO is trying to get far enough away from your planes to push them off the edge of the map". Depending on what UFOs you identify as intercepting, you might well choose a different combination of interceptors.
One idea to put forth is the idea of having a two pilot interceptor where you have one pilot responsible for flying and the other for weapons. This would be an interesting variation if you go down the path of pilots with individual skills - you might get a better impact from a good pilot and gunner flying together but eggs in one basket etc.
"The idea is that combatants can move through clouds freely but they would block the fire arcs of weapons (and missiles wouldn't make course adjustments while flying through them)." - this makes no narrative sense. Unless the missile is TV-Optic guided like a Maverick anti-tank missile, there is no reason why a heat seeking or radar guided missile would get confused by a cloud. What makes narrative sense would be to classify the clouds in the following way:
Light clouds - has a relative small aiming penalty when firing cannons or any weapon where the pilot would presumably put the target in the cross hairs and pull a trigger. Missile act as normal
Heavy Clouds - can be used to hide in with high aiming penalties when firing cannons to the point you 'd probably avoid using such weapons.
Thunder Storm - RARE. As per heavy clouds but with the added penalty of playing havoc with the electronics and aiming systems of missiles. There could be visual clue that a bolt of lighting will happen in the next turn which may alter what you planned to do next.
"we'll also likely be experimenting with some other types of equipment that weren't in X1, such as turret weapons that are capable of rotating their fire arcs, or shields." - arrrrrrrgh. Turrets on a plane, god no. Logically these turrets are computer controlled so would either be 100% accurate and OPed or as bad as the turrets in Star Wars or the original Battlestar Gallatica which despite being radar and computer controlled never actually hit anything except for its own ship and only actually hit when the craft flew directly at the turret (and even then took several shots before it hit). Special equipment I'd like to see (and I'm not an expert so some of these might already exist)
External fuel tanks to increase the range of crafts.
JATO rockets - these are used in real lift to help heavy aircrafts take off on shortish runways. In X2 then this would mean the aircraft could go from the back of the screen to 2/3rd up and enable it to be in range for its cannons in one turn. Each rocket is usable once per mission.
Parachute - kind of an anti-JATO rocket that means an aircraft close behind the UFO and in danger of being destroyed can rapidly lose speed and drop out of the battle. Usable once per mission and when used almost guarantees you won't be hit upon retreating.
"Fake Damage" pod. In WW2, some submarines had compartments which when released would see a load of oil and metal float to the surface and to fake a sinking so that the destroyers above would stop dropping charges and leave. Maybe a device that fakes damage to the aircraft so that the enemy assumes is fatally damaged and will target a different aircraft instead?
Cloud Projector - if you are going to have clouds then you could have a projector that shines a light of your ship in front of you and "project" an image of a ship in front of you. This might fool some types of enemy weapons.
"With regards to pilots I'm just thinking that each aircraft gains experience in combat and can level up perhaps three or five times, and gains +Accuracy on its weapons and +Evade on the plane. " - this doesn't make narrative sense. Why would an aircraft get better because it survived a mission?? It would make sense to keep the aircraft itself remain the same (with the same default characteristics if you copied the 3 aircraft types I mentioned earlier) but the pilots improve. As per the soldiers you could have a skill for
flying (modifier when avoiding attacks),
shooting (modifier for shooting accuracy - different skill for missiles and cannons?)
Stamina (less important in a fight, but pilots need to sleep and recover between flights and the better the stamina the quicker to be at 100% when next flying)
Bravery which determines if a pilot will fire missiles at the maximum range or is prepared to get in closer when the odds of hitting is maximised.
On top of this, some pilots might get random "specials" such as:
Quick reactions - bonus to evasion
20/20 Vision - not impacted by aiming penalties in light clouds (see prior comments)
Mechanic - is able to make minor repairs in flight and therefore recover a small amount of aircraft health (repairs capped so not OP)
Short Sleeper - suffers from Short Sleeper Syndrome which means they need minimal sleep to function.
Linking together all my air module comments, upon identifying a UFO in the sky, the first bit of strategy is to decide on the aircraft type (three small aircrafts to take on a drone or scout type ship or some heavy hitters against a bit battleship?), the type of pilots (so you might use one small aircraft as a decoy with a Quick Reaction pilot with a couple of big hitters) and then have a decision on weapon make up.
"Obviously asking players to issue orders to all of their planes every few seconds wasn't an option as every combat would take hours"
Here is an idea that would make it work - you only actively control a single fighter and at the beginning of the fight at turn zero you issue orders of how you'd want the rest to fight. So if you are fighter one (on the left hand side) you can select fighter 2 (on the right hand side) and give the order:
FOLLOW ME + IMITATE
with such an order, when you move your fighter forward and shoot a missile, fighter 2 will also move forward and shot a missile. If in the next turn you hold position and shoot your cannons, then fighter two will also hold position and shot their cannons. Other variations could be:
FOLLOW ME + FIRE AT WILL - will copy your position but will shoot if a weapon is in range.
FOLLOW ME + FIRE AT OPTIMUM RANGE - will copy your position but will shoot once once it has moved a block closer than the maximum range of the weapon.
For fighter three (in the middle of your fighters) who might be a heavy hitting fighter, then the order might be:
SHOOT AT MAXIMUM RANGE
at which point it will advance until in missile range and will fire off missiles each turn until it has run out - at which point it'll advance until it gets into range of it's next weapon (say cannons). Other options could be
ADVANCE AND SHOOT - fighter will keep moving forward and will use the most powerful weapon that is in range
ADVANCE AS DECOY (PURE) - fighter will make itself the most advanced fighter and will adopt evasive manoeuvres (bonus to evasion - maybe the ship could do a wiggling motion to reflect this)
ADVANCE AS DECOY (POT SHOT) - if the enemy shot at a different fighter in the previous turn, it'll fire a weapon to get the enemy ship's attention that round.
KAMIKAZE - the fighter is a shot away from dying and is too close to run away then why not Thunderchild it heroically? And congratulations you get the "Ram Raid" achievement.
There are other simple commands you can do - "ATTACK NEAREST" if there are multiple enemies etc. Once you have selected the order then the computer will carry it out while you focus on just your craft. Of course there is always the option to radio new orders (that'll come into effect the follow turn)
The main complaint is the need to constantly give three sets of (probably identical) orders every turn *yawn*. There is nothing to stop you from creating a set of default battle plans in the hanger that you can select based at the start of the battle.
"If an aircraft is shot down shouldn’t there be a chance that the pilot ejected? Perhaps new missions to rescue downed pilots"?
(copied from someone else's post) If Chris isn't into the idea of you wanting to rescue your downed pilots in principle then it would be a great one off side mission where the reward is one kick ass elite pilot levelled to however far you are in the game at the time.
Edit: an idea I forgot to add:
Camouflage painting of your aircrafts.
If have a choice of paint colour schemes for your aircraft:
Sandy - makes the fighter harder to see and hit if over a desert
Blue - makes fighter harder to see and hit if over the ocean
Night Sky Black - make fighter harder to see and hit if fighting at night.
Snow White - makes fighter harder to see and hit if fighting over the north or south pole.
Green / Brown - makes fighter harder to see and hit if fighting over the Amazon rain forest etc.
Depending on where your base is might see your fighters doing more combat over certain terrains more so there might be a minor advantage in your colour scheme, although you will probably be punished if painted in Snow White at night and vice versa.