Install the bookmarklets

Drag a button to your bookmarks bar. The loader fetches the current code from https://tic.khodok.com every time, so it updates itself whenever the site is deployed. The standalone carries the code with it — use it on sites whose Content-Security-Policy blocks the loader.

• Ultimate Tic-Tac-Toe the game — two players at one keyboard
  Ultimate Tic-Tac-Toe Ultimate Tic-Tac-Toe (standalone)
• UTTT: computer opponent run after the game is on screen
  UTTT: computer opponent UTTT: computer opponent (standalone)

Multiplayer is not a bookmarklet: a page's Content-Security-Policy controls what its scripts may connect to, so it lives at https://tic.khodok.com.