Going back a bit to the “writing-based puzzles” concepts, I think it would be fun to have inline-editable and draggable elements in the world. Not necessarily on a meta level (e.g. dragging a giant boulder out of the gameplay area to remove it from the game), but for tactile puzzle solving. It could be particularly useful for mobile users (more touch, less type).
Examples:
- Flipping an On/Off toggle on a device.
- Dragging a “key” text onto a “lock” text.
- Filling a flask with water by dragging the text onto yourself.