A single integer N = a complete chess game

[Hans Havermann]

Maximilian Hasler wrote:
>>>> [FIDE definition of legal position elided].
>>  I said the largest known number of plays, not plies. There is a position
>> from which White can choose from 218 possible plays. The position,
>>  http://www.chessbox.de/Compu/schachzahl2_e.html
>>
>>  is, as far as I can tell, legal.
> 
> 1/ I agree that here "plays" might be more appropriate than ply.
> 2/ The elided definition implies that this position is not legal.
> 


Why isn't this position legal -- please enlighten us?