Important why the reference is valid as well, is that endgame is rhetorically near ‘Endlösung’ (ultimate solution) and ‘Endsieg’ (ultimate victory), meaning complete genocide as ‘solution’ to ‘the problem of the jews (existence)’ ( ‘Judenfrage’ ) and world domination as solution to the growing extremes of the Second World War.
Please don’t use ‘Endlösung’, ‘Endsieg’ and ‘Judenfrage’ in casual speech.