LCADolby just hit the nail on the head. $15 a month, relative to the competition is a pretty high premium for a game which at first glance appears to have very dated graphics.
And to take it a step further look at the other competition. There are a lot of newer games going with a free to play, pay to win pricing model (Need for Speed world for example). In these games anyone can get an account and play for free, albeit with several features cut down. Where they make their money is on the premium features that are often quite costly. But the point is this attracts a large and active playerbase that maintains interest in the game and for people with deep pockets it sells big. Again taking the example of Need for Speed world, they just passed 10 million accounts. And on the money side? One of my friends dumped over $500 USD in a one month period on NFSW, I myself am guilty of dumping close to $200 into it. HOWEVER, and this is a huge point, I *don't* ever have to pay again to play the game with the features I've unlocked. This is a very attractive alternative to maintaining a monthly fee endless under threat of losing access to the game if I ever stopped paying. It's for this very reason I haven't had an active Aces High account since since September. Over the past ~10 year since I discovered Aces High I've been on and off with paying for an account for several months at a time (4 months on, 3 months off, etc). When I didn't have an active account I used the free H2H feature while we still had it.
Here's the other catch. Aces High is not a persistent world game at least not in the sense of having any meaningful longterm stats. Another trend I've noted in video games in general is the tendency of all of them to start having player career accounts and level ups, particularly in first person shooters and such (Battlefield 3) for example. I guess for some people it doesn't matter what game they're playing they gotta have that gratification that comes with the level up treadmill and the next little goal to unlock some little perk. Generally, I am against this as I never enjoyed this aspect of gaming, but it has become so pervasive I have to think it must be driving sales for a lot of these games. In Aces High the *only* stat you carry with you through a map reset is your perk count and you don't even maintain this if you deactivate and reactivate your account. There are no level ups, no achievements, no medals. Nothing to indicate any history behind a player. In fact you see more of it on this forum with people driving up their post counts just a get a title like 'plutonium member'. While personally I don't take anything from these things, I can't deny they probably drive sales.
Finally, there is the realism and learning curve of Aces High. I've had a lot of friends I've tried to get into the game. But with no experience in what it is actually like to fly a plane, and the difficulty of actually successfully winning an aerial battle they typically give up after the first month or two. A lot of the time they never even managed a single air to air kill. This game is geared pretty hard toward a niche market because of this complexity and realism. Personally I appreciate that and it actually makes me want to play the game more than say Battlefield 3 where su27s loop around at 80 knots and pilots hop out mid flight to fire an RPG at their opponent's plane, then hop back in and fly away. My point is to the average gamer this game doesn't carry the same appeal.
When you put it in this perspective you can see why Aces High's playerbase has shriveled over the years. I don't know what could be done to really change this, although I think a pricing model change could definitely be in order. It might be interesting to make the base game free to play with all planes below say 40 ENY available with some sort of pricing scheme to unlock planes below 40 ENY. Perhaps even have some unlocked using an in game cash earned from successful sorties, or even require the payment of in game cash to use the heavier ordinance, or ammunition loads.
