Most people already know the tricks used by supermarkets to persuade us to spend as much money as possible: the smell of fresh bread pumped to the front of the stores, premium brands placed at eye level on shelves, confusing pricing systems...
However, less well known is the tricks used by another set of unscrupulous con artists – the makers of free-to-play games for smartphones and tablets.
Seldom a week goes by without a news story about a kid running up bills of thousands of pounds by simply playing a game on their parent's iPhone.
There are of course pretty simple ways to prevent this happening. Make sure that you are unable to make in-app purchases without entering a password, and then never ever give your kids the password. Easy peasy.
If you haven't done this already on your own phone then go do it now. Go on. Quick! Run! Your six- year-old is probably plunging you into bankruptcy as you read this!
If you are unsure how to set up a password on your phone then this site has a list of the more common brands.
Ok, done? Good. But that was only the first step.
You may have averted the immediate risk of you needing to sell one of your kidneys, but in order to be truly safe you need to educate yourself and your kids into being informed and canny consumers. Because even if your kids have never lost three grand to these shysters I bet you've dropped a couple of quid to get to the next level of something like Candy Crush.
I should say at this point that I don't object to the free-to-play model of games. But you have to remember that these guys aren't working for free. They have to get their money somehow. And I'm sure that most people would never agree to pay the same amount up front for one of these games as they end up paying in dribs and drabs for in-app purchases.
Here are some of the tricks that they use to separate you from your money.
Alternative currency
Instead of telling you the real cost of an in-app purchase you pay for them in Gold Coins, Game Gems, or something similar. This masks how much you're actually paying for something and helps you forget that it's real money you are spending.
And of course there will probably be a couple of hundred coins/gems left over from your purchase which aren't quite enough to buy something else – tempting you to add a few more to the pot.
In addition there are often "discounts" for bulk purchasing of these currencies, fooling people into thinking they are actually saving money.
Switching From Skill to Money Games
In the early stages of the game players can progress by skill alone. However as time goes on it becomes increasingly difficult until a point is reached where it is practically impossible to progress without buying an upgrade of some sort. The criteria for winning slowly switches from how well you play the game to how much money you are willing to spend on it
Once money has been spent on a game the player feels more invested, and more willing to spend more money. Eventually ability to achieve in the game has no relation to any form of ability and is purely about how much cash has been spent.
Candy Crush, the most profitable iPhone app ever, is a good example of this.
Methods that games use to transition from skill games to money games include:
Progress Gates
These come in two forms – hard and soft. A hard progress gate is a mechanism that does not allow the player to go past it without spending money. A soft gate is one where the player can get past a stage eventually – but it takes a great deal of time or effort all of which can be avoided by a small payment to hurry things along.
Boosts
Again these come in soft and hard varieties. A soft boost is a one off instant effect "cheat" that improves your performance in some way (makes your character quicker, gives you extra lives, etc etc). A hard boost is something that permanently makes the game a little easier, until of course it becomes so difficult again that another hard boost is needed.
Social Gaming
Many games announce scores on social networks like Facebook. Many people enjoy "showing off" their scores. And spending money is a great way of increasing those scores. Until of course your friends start spending that little bit more to beat you. And seeing as though you've already spend about a fiver getting to where you are now what's the harm in a quid or two more?
These examples just scratch the surface. I got all my information for this post from this very well researched article, and heartily recommend it as a jumping of point for further reading into the subject.
I honestly believe that ensuring our children know about the manipulative nature of things like free-to-play games is a important responsibility of parenthood. This is the kind of vital life skills that are never going to be taught in schools. It is our duty to make sure that our kids (and ourselves) know exactly what we are getting into when we download that "free" game.
How about you, what's your attitude to free-to-play games? Are you able to resist spending any money on them? Are there any tricks they use that I've missed?
Dan lives in Yorkshire with his wife, three children, and a flock of megalomaniac chickens.
Blogs at: Cabbage Dan
Twitter: @cabbagedan