How to score the play of this Cribbage round?
3
3 scores 2 for the pair
3 scores 6 for the triple
3 scores 12 for the quadruple
4 scores nothing
4 scores 2
5 scores nothing
5 scores 2.
And then that last play also scores 1 for being the last card played to that series, since the opponent has no cards to play and must say &quot;go&quot; at that time.

None of the plays scores a run, as there are other (foreign) cards that interrupt the runs.
Bicycle rules:

it is important to keep track of the order in which cards are played to determine whether what looks like a sequence or a run has been interrupted by a &quot;foreign card.&quot; Example: Cards are played in this order: 8, 7, 7, 6. The dealer pegs 2 for 15, and the opponent pegs 2 for pair, but the dealer cannot peg for run because of the extra seven (foreign card) that has been played.