F2P games usually sell game currency. Some - only one, others - several at once. Some - in retail, others - in bulk. The problem arises if the project initially existed in conditions of unobtrusive frivolity, allowing the players themselves to indicate the desired amount of virtual “tugriks” to buy, and then suddenly decided to switch to wholesale trade. And in general, is it economically justified to impose currency packages with a flexible discount system on users? We have tried to answer these questions, having successfully endured difficult, painful economic reforms in “Tanki Online”.

The root cause of the change was our desire to increase revenue per paying user (ARpPU). And before we rush into the abyss of desperate reforms, we took a whole series of tentative steps in the form of discounts. The temporary decline in prices for content or for crystals (the virtual currency of Tanks Online) in one way or another pushed the audience to increase their spending. In general, these experiments were successful, but remained at the level of one-time actions, while we needed a system. And we built it on the basis of a batch sale of crystals.
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As you know, innovation in business will not work if it does not benefit your customers. Therefore, in addressing the players, we focused on convenience and benefit. First, we simplify the decision to purchase and minimize the time for its adoption, offering a choice of all five options. Secondly, the larger the package, the cheaper it costs the player each crystal in it.
I must say that the buyer does not know how to choose and does not like. We can recall the Tire Iyengar report on the problem of choice. If you didn’t watch it, we strongly recommend that you go to YouTube and type in “Sheena Iyengar” in the search box.
The bottom line is that a user, going to the supermarket and seeing more than a hundred types of apples there, will be very happy with such freedom, but in the end, he will hardly make a choice that will be satisfied. And if you imagine that there are only seven kinds of apples, say, then the choice will be made fairly quickly and painlessly.
So it is with us - before the introduction of the mechanism of package sales, the player had to calculate how many crystals he would need. Take with a margin? Or, conversely, smaller, and the rest to accumulate? Head bursts of questions. And the difficulties did not end there. Having decided on the number of crystals, the player drove it into the appropriate field, estimated the amount in real money, and only then went on to pay. Too long. Too dreary. We wanted to reduce the decision making process to a single intuitive click.
But before putting the old payment mechanics under the knife, we turned to the practice of the market and this is what we got.
1. Packages must be ordered by size. Either from top to bottom, or from bottom to top - depending on what logic the design of the payment page implies.
2. Packages must have a bonus. This is a simple incentive for users to purchase.
3. The bigger the package, the bigger the bonus should be. At the same time, the bonus should grow a little faster than the size of the main amount of the package grows so that it does not work out that it is more profitable to buy two small packages than one large one.
4. The default package should be in the middle. It is necessary to hint to the player transparently that it is the purchase of an average package that is an average, i.e. most popular solution with other users.
In order not to be unfounded ...


How many packs do? This was the next question that required careful study. As a result, we decided to dance on the size of a person’s short-term memory. Experts usually call numbers from five to nine points that a person can simultaneously hold in a short-term memory. We chose six - a good number, an even one, you can beautifully and symmetrically arrange packages on the page.
So, we decided on the basic principles of the calculation of packages and their number. Further, we fixed the minimum and maximum packages based on the prices of game content. It would be wrong to equate the most expensive game item to the size of the largest package. But correctly make them one order.
And then - the matter of technology. We unloaded the sizes of all payments for a certain period, looked at how many crystals our players buy. And to our surprise, we found that users have long identified for themselves a kind of "packages." Statistics showed that the audience consistently takes quite certain amounts of crystals. Portions of 500, 1000, 5000 and 10,000 crystals were the most popular.
Having at hand the basic principles and limitations, the number of packages, as well as the size of the minimum and maximum packages, and based on the existing statistics on the preferences of players, we reduced the calculation of packages to the simplest linear optimization problem. Such are well solved, for example, in the add-on “Search for a solution” for MS Excel.
The few that we added “from ourselves” were intuitively supposed to round up to thousands of crystals. And after that we looked at home appliances stores and subtracted the ruble from the price of each package. It was 100 rubles, it became 99 rubles. It was 3000, it became 2999 rubles. Minus ruble - an ancient, but true method of marketing.
However, not everything was smooth, and some nuances had to be taken into account, having already built the system as a whole.
1. Prices type "99.9" is fine, but not from a technical point of view. If for 99 rubles we give 5000 crystals, how much should we give for 100 rubles, considering that the price of one crystal is exactly two kopecks? It turns out, also 5000. And for 99 rubles 50 kopecks? And for 101 rubles? Man, everything is clear, but billing, unfortunately, not a man. So, at the price of beautiful prices, let us have small, but crutches in the code.
2. What to do if a person came to the terminal, holding in his hand 150 rubles, and we have packages for 100 (99) and 300 (299)? Terminals for the most part have not yet learned how to surrender change. And what if the user pays via SMS? You cannot create a package for each SMS-point. But what if the player has a prepaid card for $ 10, and he intends to spend them all? Having thought about these questions, we gave up and left the user the opportunity to enter an arbitrary amount. Now, the entered amount is optimally spread over the packages, and the player receives the top bonuses from these packages in full. Strictly speaking, this rule is not exactly a batch sale of currency, but rather a stepped discount on crystals, but we accepted this violation of the principles originally laid down. Also, in the sacrifice of this logic and design had to bring one of the packages. There are five of them left, and with the sixth button the user can enter any amount he needs.
3. Finally, the third problem we faced is the problem of “beautiful” amounts in other currencies. We calculated prices of the type "9.99" for rubles, and if the user pays in dollars or euros, then all the beauty disappears. But we did not want to change prices for different localizations. Beauty requires sacrifice if it is not about price discrimination.
Finally, everything was settled, and we put the packages on the base. In this form, they are preserved to this day.

We achieved our goals. Buying crystals has become both easier and more profitable for the user. Well, we are not a loser - ARpPU grew by 30%. Win-win.
What's next? A lot of thoughts. For example, targeted packages. Knowing how much a player pays, form packages specifically for him. The decision is obviously controversial, but there is also a light version of it - not to show large packages to a player who has not yet done enough not to scare him away with large sums at the stage of getting used to the game. And it is also possible, as in “Kinder Surprises”, to invest in packages of a more profitable denomination a random game item. But that's another story.