The aim is to capture cards from the table, especially spades, aces, big casino (10 of diamonds), and little casino (2 of spades). A card played from the hand may capture by:Pairing that is, by taking all other table cards of the same rank as itself. It is the only way face (court) cards can be taken.
It appears to have come from the fact that there was a time when video poker machines or "Cardies" were in pubs and clubs as well as the slots - they were all called poker machines. This like most slang was broken down to pokies probably due to people saying things such as "I'm off to the pub to play the pokies".