https://www.reddit.com/r/Terraria/comments/6qwod3/any_runescape_players_here_ive_just_released_my/

(second time posted this, first one got deleted?)

Thank you so much for bringing this to my attention. If it is not a good friend on Runescape kept on telling me Terraria is a great game. And that I know GOG is DRM-free (Since I love play offline). I would not have purchased Terraria at all. I love the game so far, Must have played for over 60 hours+ on Terraria without any mods

I don't know how to use mods for Terraria though, I will look it up how to add into the existing worlds without me losing all the progress thus far.

The steam version you can also play offline, that's the version I use.

Having said that, I also use Tshock for personal servers.

You should be able to make archives of your saves easily enough. PCGamingwiki may show where gog versions are.