Just finishing up the challenges for day 31. The second challenge asks you to add a bar button to allow you to start a new game. I added this but then realized that when it was pressed, the list of usedWords remained. To fix this, update the startGame method to the following:

func startGame() {
        if let startWordsURL = Bundle.main.url(forResource: "start", withExtension: "txt") {
            if let startWords = try? String(contentsOf: startWordsURL) {
                let allWords = startWords.components(separatedBy: "\n")
                rootWord = allWords.randomElement() ?? "silkworm"
                usedWords.removeAll() // this is the added line
                return
            }
        }

        fatalError("Could not load start.txt from bundle.")
    }

If you just replace the .onAppear() with below code, it's done..navigationBarItems(trailing: Button(action: startGame) { Text("Restart Game") })