Event - unit dies (or whatever the trigger SHOULD be)
Condition - the great king of donkeyland has arrived (or something that fits your desired condition).
Action - exactly what you've said.
You cannot refer to the picked players before picking them, so the event and the condition cannot check the picked player. If you wanted to do that, you'd pick them, then do an if then within the "pick actions" where the "then" would be to end game for the picked player.