Riptide GP2 supports 3 different multiplayer options, although not all of these are supported on all platforms.
Online Multiplayer - Log in with your account and play with others over the Internet. You can play with randomly matched opponents, or with Friends using the Invite feature.
Supported Platforms:
iOS (using Game Center)
Steam (using Steam ID)
Xbox One (using Xbox ID)
PlayStation4 (using PSN)
Note that online multiplayer is no longer supported on Google Play.
VR Challenge - Race against ghosts of your friends as you try to set the best time on each track.
Supported Platforms:
Android (using Google Play Game Services)
iOS (using Game Center)
Steam (using Steam ID)
Amazon (using Game Circle)
Windows Store (using Google Play Game Services)
Xbox One (using Xbox ID)
PlayStation4 (using PSN)
Split Screen Multiplayer - Race against multiple friends on a single device! Connect 2 or more Bluetooth or USB game controllers (or a Smart TV remote control) to your device, and run the game. The screen gets divided into multiple small screens, one for each controller.
Supported Platforms:
Android
iOS
Steam
Amazon
Xbox One (supports up to 6 players!)
PlayStation4