hacking unity game

Hi .

I use a decompiler to edit Assembly-CSHARP , I made some basic hack .
the game I am trying to hack is new, and it's Developer first's game , the game uses photon networking
and the Developer said , that there is no serverside in his code

I was wondring how to alter the others players code , since I saw some hacker do that .
Thanks in Advance .

I'm kind of curious as to which game this is. He did not alter other player's codes he just abused the networking system while sure you know he uses photon networking but what's more important is what gets sent over the network and what stays on the client