  The 2-player impartial game of Wythoff Nim is played on two piles of tokens.
A move consists in removing any number of tokens from precisely one of the
piles or the same number of tokens from both piles. The winner is the player
who removes the last token. We study this game with a blocking maneuver, that
is, for each move, before the next player moves the previous player may declare
at most a predetermined number, $k - 1 \ge 0$, of the options as forbidden.
When the next player has moved, any blocking maneuver is forgotten and does not
have any further impact on the game. We resolve the winning strategy of this
game for $k = 2$ and $k = 3$ and, supported by computer simulations, state
conjectures of the asymptotic `behavior' of the $P$-positions for the
respective games when $4 \le k \le 20$.
