First, thanks for posting.
Tldr: Ambassador is strong!
I think this board is clearly an engine with Amb, Tournament, Village, Margrave, Lighthouse, HoP. So I think your mistake was
Chris Rebman: turn 1
Chris Rebman plays 3 Copper
Chris Rebman buys Silver
You really want to get an Ambassador, to clear out your Coppers/Shelters to get an engine going an increase the chance of Tournament/Province collision, and get some of these into your opponents deck as long as they can't play Lighthouses every turn.
My plan would be to win the Ambassador war, for this open Amb/Lighthouse or Amb/Amb to get rid of Coppers (maybe keep one for HoPs). I would probably do the first and get a second Ambassador later. From this try to build on again, probably with Tournaments if my opponent does not have lots of Provinces already. The prizes are not that threatening, Followers is partly countered by an engine with Ambassador, and hard-countered by an engine with two Lighthouses. The steed is nice but non-essential, Princess is strong in an engine but underrated, so you will probably get it anyway against most opponents that prefer Followers/Steed, even if you are not the first to pick a prize. [edit: also, if your opponent goes the direct way to Provinces, Princess is not that valuable for them as it is to you] In summary, not so bad here if you lose on prizes, though you really want Princess.
Stay as light on Treasure as you can afford, get some HoPs asap, get them to $5 should be easy (Mistrel, Magrave, Tournament, Lighthouse, itself), and to $8 also not hard with some Prizes and Treasure and Amb and Necro. Get the engine running to draw the whole deck, get a second Lighthouse to play one every turn and be immune to attacks. If you opponent doesn't do this, get a Margrave and a GhostShip [edit: and CouncilRooms], which should be really strong in combination, consider cursing with Ambassador if you are desperate.
For the endgame look if you are behind or not, either get enough HoPs to overtake and end the game or look for 3pile endings.
I think both of you went into Provinces for Tournaments too early in this game, where it more or less becomes a coin flip on who gets the Followers for this kind of game. Your opponents Ambassador probably helped them by increasing the chance of colliding. More consequent cleaning and building up should give the better chances in this kingdom, as in the end they relyably collide Provinces/Tournaments, lets you play guaranteed Lighthouses and powers up HoPs. Even if you are behind, there is plenty of opportunity to come back via Duchies with Tournaments and HoPs.
But of course, there are lots of parts that have to fit together for this kind of engines, but its worth trying, because in the end, they are not only the more powerful decks, but more fun, too...