While the goal of this deck is to aim for a OTK, it's flexible enough to continue playing if that doesn't work out.
Going Second:
You will want to go second if shooting for OTK. General strategy is to XYZ Summon Prime Photon Dragon using Galaxy-Eyes Afterglow Dragon. Detach in battle phase, and double Prime Photon's already massive ATK points.
Going First:
If going first, XYZ Summon Galaxy-Eyes Photon Lord and Starliege Photon Blast Dragon (Preferably equipped with Photon Orbital, as this will make your board state very hard to deal with)
General Commentary:
I've been working on this deck list for the better part of 3 years. Play tested against Meta, and seen lots of trial and tribulation. While it's not the best out there, it can certainly hold its own in competitive play. This is the iteration of the deck I'm currently using. Hope you enjoy playing this as much as I have making it!