Ultimate Tic-Tac-Toe for iMessage (shown as "Ultimate" in Messages)
Open a conversation in Messages, tap the apps button next to the text field, and choose Ultimate. Send the invitation. Your friend taps it and plays first, as X. Take turns; each move is a new message. The rules are behind the book button on the board.
The app has no Home Screen icon: it lives in Messages, in the apps row next to the text field.
Email alexvsaveliev@gmail.com with what happened and, if you can, which iPhone and iOS version you are on.
The app collects no data. See its privacy policy.