I used to set tiny puzzles that look like the word "Hi" just to send them in the chat as a greeting. There's no actual list since I didn't keep track of them, but if it existed you could consider today's Sister Cities / 姉妹都市 a new puzzle on that list.

Rules: Draw an orthogonal loop through the center of cells that does not branch or intersect itself. Each region must be passed exactly once. All regions that are the same size, shape, and orientation must be passed by the loop in the same way.

Finish the puzzle in 2:00 or less for a Speedy Sloth 🦥!
Finish the puzzle in 4:00 or less for a Quick Crab 🦀!
Finish with any time at all for a Greeting grey-chested greenlet 🐦!

Example (Penpa+): https://tinyurl.com/2xqqd2cw
Puzzle (Penpa+): https://tinyurl.com/2xqaua3w

Mind the GAPP vol. 43

with 5 bonus puzzles!