How we change what others think, feel, believe and do
When playing computer games, it is a common for them to offer you things you can buy. This is a funding model that may allow them to give the game away for free, especially when the game play is so compelling that players are desperate enough to spend money on game benefits.
Shortcuts are ways to save longer game play. They can be physical shortcuts, getting you from A to B without having to to via C. They can also save time and effort in other ways such as working out puzzles and generally gaining experience.
In many ways most of the other purchases are also shortcuts as they save time and effort. Other things unavailable through the game may also be bought.
The simplest thing to sell is knowledge. How to get out of the maze. Where the treasure is buried. What your opponents may do next. Knowledge is power and can give great advantage.
Resources of all kinds may be bought, from extra weapons to time available to play. Sometimes this gives permanent advantage, and sometimes it offers shorter-term benefit. Sometimes purchase saves time and effort, and sometimes the only way to get something is to buy it.
Some things may be unavailable in the game or take time to achieve. Payment can give instant access to areas otherwise inaccessible, to people and groups, to bonus play and to other desirable things.
Games, like life, are full of decisions where the outcome is unclear. And as with life the player may well regret decisions made. This gives the opportunity to sell them a replay, going back in time, undoing what has happened and trying again.
This can be very desirable in games where choices can be fatal to one's character. Paradoxically, this can be particularly profitable as players take more risks as they think 'I can always buy reincarnation'.
Enablement can be sold in various ways. The simplest way is to give the player extra skills, strength, magical spells and so on, that they can use at will. This can be permanent enhancement or a temporary boost.
All kinds of events can be bought, from acts of god and deus ex machina, to parties and storms. Things that happen are different from items. They are verbs more than nouns. When players think 'I want' they often seek actions rather than things.
The simplest way of selling things is to have a storefront where players can pick what they want. This can be available at the start, throughout the game or at specific points. Purchases can be shortcuts or items unavailable elsewhere.
In-game purchase can be particularly effective when the player is stuck, and is desperate to move on or escape a difficult situation. With care, games can be designed to make this happen, drawing in the player then precipitating events that cause desperation.
Is this pay-for-advantage cheating? Probably, though this calls into question what exactly 'cheating' is. Cheating can be gaining advantage without using skill or effort, in which case paying is clearly cheating. But when it is available to all, is that OK? Cheating implies unfairness and inequality. People with more money can gain advantage others can't afford, which is surely unfair. But that's life.
If enough dislike the imbalance that in-game purchases creates, then they will abandon the game and income for the game's managers will fall. This free-market effect acts as an effectively regulator. Social forces help too, as those who buy too much may be shunned.