For physical games, you can:

• Take a photo of the final score or board state (like showing the final chess position)

• Record a video of the final moments (like recording the last few moves)

• Have a witness confirm the result (someone else who saw the game can verify who won)

• Use the game's built-in scoring if available (like a digital scoreboard or app that tracks the game)

• The key is having clear evidence that both players can see and agree on!