I know that the answer to the question "What competitor of Microsoft already had a store?" is in "Several notable video game developers criticized Microsoft for making its Windows Store a closed platform subject to its own regulations, as it conflicted with their view of the PC as an open platform. Markus "Notch" Persson (creator of the indie game Minecraft), Gabe Newell (co-founder of Valve Corporation and developer of software distribution platform Steam), and Rob Pardo from Activision Blizzard voiced concern about the closed nature of the Windows Store. However, Tom Warren of The Verge stated that Microsoft's addition of the Store was simply responding to the success of both Apple and Google in pursuing the "curated application store approach."". Can you tell me what it is?
Answer:
Apple