A very nice checkmate...
Well, yes and no. The plan was to get a mating attack or win a lot of material while black defends mate. That plan started with 13. Nxe5. As it happened, black made some blunders which allowed the final mating combinition, and that wasn't planned from the start of course, as it wasn't forced until the very end.
A pretty standard Ruy Lopez opening suddenly devolopes into a dangerous mating threat. But as black defends aganst the threat, a much more subtle attack can begin... which led to a rather funky checkmate variation!
I've added some comments. Feel free to discuss.