Microsoft pledged to keep its app store neutral for customers, developers and competitors, a move meant to appease regulators as they consider a proposed $68.7 billion purchase of Activision Blizzard.

In a blog, Microsoft president and vice chair Brad Smith (pictured) explained it will not put its apps above those of competitors, and will apply promotion rules consistently and objectively.

Microsoft will not require developers to use its system to process in-app purchases, Smith stated.

He told CNBC developers will be free to use their own or third-party payment systems, noting a desire to run one app across different devices.

Smith told CNBC the Activision Blizzard deal requires approval from 17 regulators and Microsoft would advance its app store plan regardless of any change of legislation by authorities in a host of countries.

In the blog, Smith offered assurances on the continued availability of leading Activision Blizzard titles on competing games consoles.