Free doesn’t mean free: In app purchases
Free doesn’t mean free any more. In fact, Apple doesn’t even use the word “Free” any more: it replaced it with “Get” back in November 2014.
Developing apps costs a lot of money and all developers want to get that cash back (and make a profit). Mostly these days that means a mixture of advertising, in-app purchases (IAP) and data collection. Remember the adage: “If you’re not paying for it, you’re not the customer, you’re the product being sold.”
But most apps (especially games) aren’t harvesting your data; they’re just trying to trick you into paying further down the line when you’re hooked. And app marketers are getting smarter. Here are 10 tricks to watch out for…
(For mostly non-evil tips for app marketers, take a look at Complete guide to marketing a successful iOS app: How to make money on the App Store.)
Whale hunting: trying to catch fat payers

Developers try early on to discover “whales” – these are customers who are likely to spend large amounts of money in games.
Some games offer up to £69.99 blocks of in-app content, and believe it or not, some gamers actually pay that amount, and more over time. Some games are designed to adapt their behaviour towards gamers they have identified as whales and adjust the style of game on offer. Whales get fewer ads, decreased difficulty and lots of opportunity to pay up.
Sample the wares: free exclusives

Some games offer IAP content for free for a short amount of time. Crossy Road is a good example of this, serving up free characters for a few games before asking you if you want to pay to keep using the character.
Playing hard to get with IAP purchases

Candy Crush Saga uses this technique effectively. Charms are locked, until you earn the right to buy them. This makes the player focus on getting the IAP content, and makes it seem more valuable (even though you still have to pay for it).
It’s a neat trick because it also enables the game to spot “whales” (those gamers wanting to pay) because they’ll be working towards unlocking the IAP content. Other gamers don’t get too distracted by IAP and can be served up ads instead.
Make them wait: payers can play on

Another common technique of games using IAPs is to create an addictive, easy and playable game but then make gamers wait if they aren’t paying. Some games are upfront about the delay, while others use surreptitious techniques.
Godus, for example, has players collecting mana to spend on making game moves; the mana only appears after a set amount of time and then the gamer sits around waiting for more mana (or pays up).
Mission impossible: cranking up the difficulty

Players that don’t pay will find the games steadily becoming more and more difficult (even if the game isn’t really progressing in nature). The game gets harder and harder in order to encourage the gamer to pay for that special item, or unlock that will help them beat the enemy or bypass the problem.
Sell saves and extra lives: paying to continue

Endless runners use this technique a lot. Developers create an instant-death game, where you try to get as far as you can with a single life to achieve the highest score possible, and then try to beat your score.
How frustrating is it when you get oh so close to your high score only to die, and how tempting it would be to pay to save your game and continue. Developers use this in games with competitive leader boards to shake people down for cash.
Ads, ads, ads… then pay to remove them

Apps are increasingly serving up ads in order to make apps pay, but you can pay to remove the ads.
This is often found in non-game apps like iTube Free. It serves up adds unless you pay up £1.49. It’s probably the most honest technique used here, but be sure to use the app for a while before paying for ad-free service. And be careful to check how long the ad-free service lasts for.
Limited time offers: get your in-app purchases while they’re hot

That special gun, or extra suit… it’s only available for 24 hours. If a game thinks you’re on the fence about purchasing IAP content, because you spend time looking but just don’t pay up, then don’t be surprised if they try to make it seem more special using this trick.
Make your own money: in-app economies

One common trick developers use is to create their own virtual currency in the game. This gets players into the currency right from the start, as they earn cash as they play the game. Then use a combination of the tricks above to get them to pay real money, for virtual money, and spend that money on the IAP.