Yes, I play it all the time. (Sorry about the wall of text, ended up being way bigger than I thought after I hit reply)
1) Play Arcade battles for flying until you get the hang of it. When attacking it will give you a gun lead indicator showing you where you need to aim in order to get a hit. Here is a big secret: This gun lead indicator is wrong. Use it, but look at the aircraft you are aiming at when you are firing. You will usually see sparks, etc when you hit it. You can tell if you are leading/trailing by watching your hits on the enemy plane rather than watching your gun sight within the gun lead indicator. If the aircraft is circling around you and you are on their tail. You almost always have to fire in front of the gun lead indicator by quite a bit. It's there as an assist, not a guarantee. But in many cases you have to take the distance it calculates and you need to add another 10-20% on top of it, especially if you're circling.
2) When you play a round, based on your performance you will gain 2 potential things. RP (research points) and SL (Silver lions). These are aggregates (totals). I will explain below:
When you fight with an aircraft (or tank if you are into that - same mechanics) all your activities earn you research points and silver lions. Silver lions are the in game "currency" for buying new aircraft and for buying repairs/ammo for your aircraft after the round. Repairs/ammo are free for reserve planes so you can keep playing even if you run out of silver lions. Silver lions just get thrown into the silver lion pool and everything shares from that.
However, research points a bit more complicated.
When you earn RP for an aircraft, half of that RP goes into upgrades for that aircraft (better guns, engines, new bombs, etc) and the other half of the RP goes into researching a new aircraft. So once you max out your aircraft's upgrades, half of that aircrafts RP it earns goes down the drain.
To make matters more complicated, the RP that goes into research new planes is based on the type of aircraft you are flying and researching. If you are flying a fighter, and researching a bomber, there may be a negative RP gain, or may be a bonus RP gain. So you need to keep an eye on that. (If you hover over the RP gain after a battle, it tells you which plane gave you those RPs and any modifier adjustment.)
Once you gain enough RP's, you can unlock that plane. But in order to do so, you must spend silver lions to buy it. Then you spend Silver Lions to assign a crew to the aircraft.
3) Crew slots. These are the boxes on the bottom of the screen where you put planes. The crew is actually the pilot, and tail gunners, etc for your aircraft. As you play, they gain experience. So click the icon at the bottom of the screen and click crew. You spend points to increase their attributes (such as G force tolerance, vitality, etc). If you get a new plane but assign them to an existing crew. You need again, spend silver lions for a conversion training (think of it as flight training on that aircraft but you don't need to do anything but spend the silver lions). Once the crew is trained on that aircraft, they don't need to retrain again in the future even if you change aircraft then come back to it. I suggest when you first start off, spend all your experience on vitality. If you ever seen "pilot knocked out" when flying, this is what fixes it. Pilot knocked out means you ate a bullet. The higher the vitality, the more ammo your pilot can eat before being knocked out, and its very important to get that leveled up right away otherwise you will just die immediately.
4) Plane upgrades. Once you spend enough RP on upgrades, you will be able to change your ammo types on your guns. Some common ones are "default", "tracer", "stealth". Think of it like this: When bullets are being added to your gun (in the magazine/chain whatever it's called) there are different types of bullets. Default might have this: Normal Bullet, Normal Bullet, Tracer. So every 3rd bullet is a tracer. Now tracers do less damage but let you see where you are firing. Stealth is the same as default but it gets rid of the tracer round so you see nothing, but you have a stronger bullet in there. Once you get used to aiming, change over to stealth to do more damage to enemies. Tracer is the opposite. More tracer rounds, less normal bullets. The biggest factor for me when I'm flying is going to stealth rounds. I can usually score the highest kill rates over my team just based on changing to stealth. I always see people using tracer rounds all the time and they wonder why they don't score high on the scoreboard. My bursts might be 100 hit points worth of damage per second, and their tracer rounds do 20 hit points worth of damage per second. Makes a huge difference.
5) There really is no pay to win mechanics in the game outside of this: You get double RP/SL when you pay real life $$$. You can also pay money to level your crew faster. So they might have a slight advantage but nothing you can't do on your own given time.
6) Take whatever I said above, and apply that to each country. You have to re level the crew, the planes, etc for every single country. The only thing shared are the silver lions.
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That said, you may be wondering what the difference is between the countries. It might help to find a country that works for your play style and focus on it.
1) Americans: Really weak fighters in beginning but it opens up mid game (tier 3.) Best bombers.
2) Germans: Strong guns/cannons, but weak armor (they go down quick.) Worst bombers. They climb poorly.
3) British: Lots of guns, but small caliber and weak at first. Decent climbers. Pretty strong medium fighters. Poor bombers.
4) Russians: Very maneuverable. Good climbers. Strong fighters. Ok bombers.
5) Japanese: Maneuverable. Decent firepower. Poor armor. Decent bombers. Good climbers.
I'd say Americans and Germans are the hardest ones to start with. Russians are generally over powered across the board, so you may want to pick them to learn the game.