Being able to set custom strings means that you’ll be able to create custom text prompts to appear on the screen, and direct the player.
This is a huge step forward in convenience for custom games! Players would be able to casually try out user-created game modes, without having to slog though the entire ruleset/manual in the lobby description just to have an idea of what’s going on.
Just jump in, and follow the text prompts (that were made using the new “custom string” feature). Simple!