Do i need Photon Serever

Hello,

I have question, if i really need a photon server for game like that.

Simple game, player1 search for online or offline player2. and make a challenge(just who get highter number)
When player1 find any player2, system pick random number for player1, and send challegne to player2. Player2 can accept this challenge or decline (now or in future, even if player1 is offline), when player2 accept challenge, system pick for this player random number and just recotnized who win.
(this game what i wrote here is only example, not my life target:] )

I am very now in photon, also i use playmaker.
I already created a simple game just for send some values in real-time between 2 or more apllication, just for learn anything. But real-time game for now its not my target.

So there is my question, Do i need a photon server for game like that?

Thanks,
Gozda.