Это не просто реклама в игре. Это именно один из вариантов оплаты. Например, вы смотрите 30-секундный рекламный ролик и получаете возможность сыграть в онлайновую игру (в которой нет никакой рекламы) или приобрести виртуальный предмет, который можно использовать в игре.

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“Brought to You by Our Sponsor”
Using Advertising as a Payment Option
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In the gaming space, we offer something similar: what we call a sponsored session. Gamers get to choose to pay for a premium game session or item—typically priced from $0.25 up to $1.50—or to have an advertiser pay on their behalf in return for viewing or engaging in a 30-second video ad or interactive creative. Once the targeted and relevant advertisement is delivered, the user receives free, unlimited access to that game session or item. Our research shows that 99% of the time consumers will choose the ad-sponsored game play and items. The results for both advertiser and gamer have been overwhelmingly positive by every standard measure, including average clickthrough rates of 12% compared to the industry standard of less than one-half of one percent.
For example, for much of 2008 Sprint sponsored an entire channel of games across the WildTangent game service. Every game in the channel was available to be played for free, compliments of Sprint, via sponsored sessions. The creative included 30-second Sprint spots and branded mini-games. Even though the gamers were free to play their selected game after 30 seconds, the average time spent on the creative was nearly 60 seconds. According to a Dynamic Logic study, the campaign scored in the 90th percentile of all online ad campaigns run by all wireless advertisers, with big jumps in brand awareness and favorability.
http://casualconnect.org/content/Seattle/2009/maddensummer09...