This is not the first TTRPG, nor the first indie TTRPG, I ever played, but it was probably the one that really cracked it all open for me. Although a pretty simple solo journaling game, something about it just worked for me, and shortly after playing it I found myself with a fully fleshed out world of mechas named after Greek mythology, space pirates, and a pilot trying to figure out their strange connection to their mecha.
The game itself is spare, only a cover page and a single page of rules, but those rules primed me for some serious creativity. The central premise is that you're a mecha pilot who will die at the end of a 24/32-episode anime, and the primary mechanic of the game has you roll a d6 to determine how many episodes further into the show you proceed. You start on episode 1, journal what happens to you, then jump forward by however much you roll on a d6. You could finish the whole game in 4-6 rolls if you got (un)lucky, but on average you're looking at something more like 7-9 rolls. This kind of sporadic progress through the artificial arc of a set episode count really challenges your ability to fill in the blanks in between what you explicitly see/write, which was something that I really enjoyed about it.
If I have any criticism of the game, it's that it really relies on you already knowing the tropes of mecha anime since its framework is so spare and simple. It certainly made it a little difficult for me, someone who isn't super well-versed in the genre, but solo journaling games like this have helped me start to let go of the idea that things have to be 'correct' or 'perfect' or even 'all that good' for me to still get enjoyment out of them. I salute you, plot ARMOR, for your service to the hobby.