Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2014

Summary of significant accounting policies [Abstract]

Property, Plant and Equipment, Estimated Useful Lives

	Estimated useful lives
Servers, computers and equipment		3 years
Furniture, fixtures and office equipment		3 years
Motor vehicles		5 years
Leasehold improvements		Shorter of lease term or 5 years

Useful lives of finite-lived intangible assets

	Estimated useful lives
Game licenses		1-3 years
Software licenses		2-3 years
Capitalized development costs for internally generated software		1-2 years