N Terraria Season 3 was a continuation of Season 2 in the new-at-the-time version 1.1.2 with changes in most of the game. One of the most notable changes is that the mod is harder than the others, and it had more events than newer versions. It is also one of the first seasons of the mod to get multiplayer support. A compatibility version of this mod version was released a few months ago for testing, but since It is made by Nakano, for testing most likely means for fun.
The compatibility version is the one named "N Terraria 3r", which has been made to run on Terraria 220.127.116.11.