Historically, many game developers have turned up their noses at the concept of in-game advertising.

But as the paid game market has declined, and the F2P games market has got more competitive, attitudes are softening.

This change is something that's been highlighted by Millennial Media, which has just announced its 2015 State of the Apps report.

It's a global survey of application developers and publishers that attempts to get a pulse on the app economy.

Ads for all

Its headline finding is that 85% of developers and publishers monetise their apps, games and mobile websites in some way, which is up 12 percentage points from 2013.

And advertising is a key part of this mix.

Across the entire ecosystem, 82 percent of developers use advertising which is up from 73 percent in 2013.

The percentage for game developers is slightly higher - 89 percent - of which 35 percent use video ads.

It's the fastest growing part of the mobile advertising sector, and as Crossy Road developer Hipster Whale demonstrated with its announcement of $1 million of revenue from Unity Ads, a highly lucrative one, too.