Please note: development of Photon TrueSync & Thunder is ceased and we will not publish any further updates. While existings apps are not affected, we recommend to migrate apps that are still in development. Please read here for more details.
Photon Thunder is a replacement port of Unity's UNet HLAPI to use Photon infra structure, with complete support for all features of UNet's matchmaking API, also adding custom features from Photon.
For communication, Photon Thunder features cross-platform STUN-based NAT punchthrough, keeping the reliable Photon relay as a fallback option.
Except for a few optional features of the matchmaking systems, Photon Thunder has the same API as Unity's UNet HLAPI, so porting an existing multiplayer game to it should be a matter of changing a couple of scripts and menu prefabs.
Quick Comparison Of Thunder And UNet