Obligation: do not say that symbol that is fifth in our latin script (or similar looking glyphs). Don't just drop this glyph, but find a distinct way to say things.
Oulipo is a game we play in the #oulipo channel on IRC on tilde.town where the letter e is forbidden in all forms of communication. It is fun and challenging!
Wikipedia: https://en.wikipedia.org/wiki/Oulipo
A mastodon instance: https://oulipo.social
Gadsby, a novel written in oulipo: https://archive.org/details/gadsbyastoryofov47342gut