Rating:

This was intended to be a beginner challenge accessible to anyone even without any crypto experience.

tdlr;
- there are lots of things that we can notice about the ciphertext
- the first word has an apostrophe, we can probably guess that it says "You're" or "You've"
- trying to find a pattern (and taking hints from the title), we can see that each character is shifted by its index in the ciphertext (excluding punctuation and spaces)
- some manual work can be avoided by considering only the part of the ciphertext that looks like the flag

[DUCTF GitHub](https://github.com/DownUnderCTF/Challenges_2020_public/tree/master/crypto/rot-i)

[writeup](https://www.josephsurin.me/posts/2020-09-20-downunderctf-2020-writeups#rot-i)

Original writeup (https://www.josephsurin.me/posts/2020-09-20-downunderctf-2020-writeups#rot-i).