It is. The author of the repo wrote about it here in German: https://thevamp.cc/2013/10/12/terraria-1-2-decompiling-und-s...

From what I can tell this was originally motivated by bugs in the German version of the game. Back then 1.1.2 was to be the last version of Terraria (a running joke at this point, they announced 1.4.4 a little while ago) and so decompiling seemed like the best option to get those bugs fixed. This might be a more interesting blog post on that topic: https://thevamp.cc/2012/07/16/terraria-1-1-2-zu-terraria-1-1...

Yeah, Im not sure why we are talking about decompiled code.

"I know that this is a real mess. But back in the days the decompiler was not so good to create super fancy code and I was to lazy to rewrite thousands lines of code."

- https://github.com/TheVamp/Terraria-Source-Code/issues/1

this looks like a decompiler's take on the "why was 6 afraid of 7" joke.

it would seem decompilers are not that funny.