It could be a game-changer. Project Fi, the search giant’s expansion into the mobile game, is a wireless service aiming to provide better access for less. It automatically bounces users to the strongest available network, shifting between WiFi and partners T-Mobile and Sprint. Customers only pay for what they use, getting money back for unused data. For now it’s invitation-only and just works on Nexus 6 phones, but many hope it will grow and squeeze out today’s fixed-rate data plans.