Ooh, great topic!
I've played RPGs before and been part of a couple long campaigns, but wasn't familiar with 1 page RPGs. I've been really enjoying the breadth and creativity of what is possible in this art form, and how cool this community is.
1. I thought I could get my feet wet by making something for fun in one day. I ended up going through 4 major drafts, spending 20+ hours over 7+ days, spread out over a couple weeks. I've done 7 video game jams so far this summer and 5 of those video games took less time and effort to make than this one page of text did.
2. I think somewhere in development I forgot that my game was supposed to be fun and social. I was so focused on making complex instructions be understandable. When I swapped letters with my first playtester (the game is played asynchronously) and I had fun and enjoyed their letter, I was somehow surprised, because I had intended to be looking with a critical eye for what I needed to fix in my next draft. I realized I wanted to lean more into the part that was fun about it, and drop some unnecessary complexity.
3. Graphic design is hard... and so is everything else. I kept being wrong in my predictions of what playtesters would have trouble with and what would be obvious. I definitely have more appreciation for physical game design now!
4. I'd like to share "The Article Also Gazes Back" which introduced me to the term "Lyric Game." I could feel it was more about vibes than gameplay, and vibes-first game development is my motto, so even though I wasn't quite sure what to do with it at first I found myself curious and went down a research rabbit hole about lyric games. So the research vibes in the game were definitely effective :) (If anyone can recommend other lyric games to check out send me a link! I think these are the kinds of games I want to make.)