You cant play terraria with snippets of code. You need every file, every line of code for it to work. Its not a problem and sourcecode mods have been around for terraria for a long time. I couldnt go post the source code up on paste bin or anything, but I can give out an executable that installs my mod (or files to change the existing Terraria). I also couldnt just give out the whole program such that people could play it like they would play Terraria without paying.