"Freemium" PC game Age of Empires Online launches this Autumn, Microsoft has confirmed to Eurogamer.
The Robot Entertainment and Gas Powered Games created RTS, currently in open beta, releases as a digital download and a boxed retail starter kit at the same time.
"The industry in general is still in somewhat of a transition state," Microsoft Game Studios producer Danan Davis told Eurogamer this afternoon. "There are some players that still want to go down to the store and buy a retail product."
Age of Empires Online is free to play, but players can purchase content, described as packs, to expand their game.
It launches with the Greek and Egyptian civilisations.
Players can buy three types of content: civilisations, boosters and empire extras. Civilisations include a free component and a premium upgrade, which allows access to restricted content.
Microsoft announced today a "pro premium civilisation" upgrade. They are civilisations built to start at level 20 and geared towards hardcore RTS gamers.
An example of a booster pack is Defence of Crete. The co-operative competitive mode, which takes Bizarre Creations' Geometry Wars as inspiration, lets players face off against waves of enemies.
Empire extras are described as "vanity items". They allow players to customise their capital city so they are unique when other players visit them.
Packs will cost between $5 and $20.
The retail starter kit allows players to begin the game with a premium upgraded civ and unique bonus content.
Davis said the retail starter kit will "probably" be similarly priced to the digital version.
Microsoft will announce a precise release date, final pricing and retail partnerships at the end of the month.
Christian Donlan went hands-on for Eurogamer's Age of Empires Online preview.