If I "play" a card, does it count as casting it?
In the case of Golos, &quot;play them this turn&quot; means that you can either cast them if they are spells, or play them as lands, whichever is appropriate (subject to normal rules of the game and other cards in play). For example, you can't use Golos to play an extra land that turn, and you can't use Golos to cast more than 2 spells if Fires of invention is in play.
So in your case your intuition is right.


Casting Spells

601.1. Previously, the action of casting a spell, or casting a card as a spell, was referred to on cards as “playing” that spell or that card. Cards that were printed with that text have received errata in the Oracle card reference so they now refer to “casting” that spell or that card.
601.1a Some effects still refer to “playing” a card. “Playing a card” means playing that card as a land or casting that card as a spell, whichever is appropriate.