I started to play recently in 2020, when I bought the game for mobile, though I knew about it's existence since 1.2.4 and watched a lot of terraria videos. I don't remember exactly how I found it, but I was also quite fond of minecraft back then, so it probably had something related to the whole "terraria is just 2d minecraft" thing, and I most likely decided to see what the deal was. Or maybe I saw some sort of "terraria in minecraft" mod back then, idk.
At that time I was watching a lot of minecraft videos, and I just happened to stumble upon a terraria series, at that time the concept of such cool weapons, progression and stuff really impressed me and I thought it was super fun, so I got it around a year and a half ago.
Back in 2012 I watched a PaulsoaresJr video on it and found it interesting, this is also the same person who got me into Minecraft a year prior to that.
The 3rd of September 2012 was when I bought the game for the first time.
2012, my cousins and brother where playing, I was to young to actually grasp the concept of progression so my brother kind poked fun at me for it. late 2014 i kickstarted a second crack at it on mobile with two of my friends, we progressed but got tuck on duke fishoron (the final boss on mobile back then) we stayed like that stuck for several months we gave up, until my friend adien figured out how to get beetle gear, in 2015, the four of us went on to beat the duke and beat the game and still play together frequently to this day.
I started really playing it last month. It was a combination of knowing a bit about the game from looking at the wiki once or twice, liking the mobile version but not really understanding how to progress and how awful mobile control schemes were, and my friends talking about it more often recently.