Yes, POLYDACTYL is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, L 1, Y 4, D 2, A 1, C 3, T 1, Y 4, L 1.

Is it a valid word?

POLYDACTYL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

of or relating to a person (or other vertebrate) having more than the normal number of digits

Not playable in Scrabble US: POLYDACTYLOUS.