Riddell will report to We R Interactive's founder Tom Thirwall. She will be responsible for developing the gaming publisher's commercial activities, including branded content.
Thirwall said: "We R Interactive's plan is to develop new formats for brands, their products and services and Arianne will enhance our capabilities in that respect."
She joins from BBC Magazines where she was advertising director, responsible for the Homes portfolio and Gardeners World. She headed the launch of Lonely Planet Magazine and developed the BBC ad marketing website.
Before the BBC she worked at H Bauer Publishing as ad manager on That's Life, Take a Break, Bella, TV Quick, TV Choice and Real.