Sinister Shadow Games can be activated even if the effect of Dimensional Fissure is active. When Sinister Shadow Games resolves, the "Shaddoll" card will be banished instead of being sent to the Graveyard.
Because a Shaddoll"Shaddoll" card was not sent to the graveyard you do not getGraveyard, the second effect that flips a Shaddoll"Shaddoll" monster face up-up will not resolve.
The resolution of the second effect can be determined by apply Problem-Solving Card Text: can be applied to reach this conclusion. Effects which take the form "Do A, then do B" are such that A and B are sequential components. A resolves, then B resolves. For effects worded this way, if A does not resolve properly for any reason, B should not be resolved either. So if Sinister Shadow Games does not send a "Shaddoll" card from your Main Deck to the Graveyard (even if it banishes one instead), no "Shaddoll" monsters will be flipped face-up.