I call them the Towers of Annoy, because I'm ever so clever and self aware. But don't worry, we'll mix it up, make it fresh. You can only put smaller discs on larger ones, the middle ones only hold 3 gallons, and the top ones ONLY TELL THE TRUUUUUTH.
Puzzles and riddles are tricky because, as you can see in this thread, for many players they are frustratingly impossible until they are insultingly obvious. The sweet spot of "satisfying" is really narrow, so they tend to be used in optional spaces where players can deal with them only if they want. Visual puzzles are a go-to because there's rarely an immediate "Wrong, start over!", so you have a chance to, well, puzzle it out. Text riddles are a pain in the butt when you don't have text input, because unless you gate the answer behind some artificial stat thing or plot device, the solution has to be right there in the dialogue list. Unless you break it out across multiple characters, but that's just a lever puzzle disguised inside character models, like I did with the rhetoric puzzle in Jade. Plus people can just guess and reload until they get the right answer, unless the writer is a jerk and randomly changes the riddle every time you reload the conversation. That would just be mean and spoil an otherwise relaxing visit to Durlag's Tower. Who would do that?
So yeah, puzzles. We'll probably have some. You're welcome, and/or I'm sorry?