Also, alchemist does help moats connect with festivals, making it very likely that each festival/moat is basically a market.
Not only were his Festivals and Moats effectively Markets (well, the combo gives half as many Buys as Markets, but there wasn't a need here for more than 3 buys in any given turn), but they were Markets where
every other "Market" cost only $2. With Festival's natural +Buy, it was simple for Marin to get what was effectively $10 worth of "Markets" with only $7, by buying Festival/Moat - something he does no less than 4 times over the course of the game.
Moat gets a bad rap usually, but it has one fairly unique trait: It is one of the only hand-size-increasers that costs only $2. (The others, of course, being Courtyard and Crossroads.) Festival is also fairly unique (and powerful) in that it gives +2 Actions
and +$2; a combo that no other card can reproduce without self-trashing (Mining Village) or luck (Tribute). Festival's weakness is its lack of draw. Moat's weakness is that it is just not that powerful. But Festival's +Buy makes it easy to pick up Moats (because they are so cheap) without slowing down Festival acquisition; and Moat's +2 Cards mitigates Festival's weakness.
Another way of looking at it: Festival/Moat together is functionally equivalent to a
Grand Market. The drawbacks are that (1) you need to draw them together, and (2) to buy them in one turn, you need $7 and 2 buys, instead of $6. The benefits are that (1)
you can buy them with Coppers; and (2) you can, if needed, buy the pieces of the combo separately on a less-than-$7 turn. If there's some way to mitigate drawback #1 - and here there was (i.e., light trashing) - the combo looks pretty solid, as once it gets going it makes it much easier to buy more "pseudo Grand Markets" (Festival/Moat combo buys). Just like Grand Market itself.
I think the key lesson from this game is that Festival/Moat is less silly than it seems.