Building on its reputation as one of the smartest mobile game marketeers, Seriously has hooked up with Ariana Grande (68 million followers on Instagram) as part of its promotion for Best Fiends as part of Apple's Apps for Earth campaign.

Providing additional firepower are YouTubers Rosanna Panisino, CutiePieMarzia and CaptainSparklez, who will be sharing their activity in the 15 limited edition quest levels.

Save the earth one IAP at a time

In these, players can buy panda characters (who replace the regular fiends), with all proceeds going to support the WWF.

You'll be able to view the resulting videos from Saturday 16 April at facebook.com/bestfiends