Exhibit 4

JOINT FILING AGREEMENT

PURSUANT TO RULE 13d-1(k)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13D shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

Dated: December 31, 2016	Landgame S.à r.l.
	By:  /s/ Gaël Sausy
	Name:  Gaël Sausy
	Title:    Manager B
	Vitruvian I Luxembourg S.à r.l.
	By:  /s/ Gaël Sausy
	Name:  Gaël Sausy
	Title:    Manager B
	VIP I Nominees Limited
	By: Vitruvian Partners LLP, its director
	By:      /s/ Philip Moritz Russmeyer
	Name:  Philip Moritz Russmeyer
	Title:    Partner
	VIP I A L.P.
	By: Vitruvian Partners LLP, its general partner
	By:      /s/ Philip Moritz Russmeyer
	Name:  Philip Moritz Russmeyer
	Title:    Partner
	VIP I B L.P.
	By: Vitruvian Partners LLP, its general partner
	By:      /s/ Philip Moritz Russmeyer
	Name:  Philip Moritz Russmeyer
	Title:    Partner
	Vitruvian Partners LLP
	By:      /s/ Philip Moritz Russmeyer
	Name:  Philip Moritz Russmeyer
	Title:    Partner