Qb8+ is a fairly obvious mate in 2. I don’t think anyone views it as a gamble.

Right. So I guess that's my quibble with the term sacrifice (shared by Rudolf Spielmann)

But what's interesting to me is the counterfactual like outside of these 3 queen moves he would have lost the entire advantage. So it was like a tactical shot like capturing the golden snitch in Harry Potter

	▲	reassess_blind 8 hours ago \| parent \| next [-]
		Sure, I get what you're saying. It's still a sacrifice, but the compensation is just mate in 2, so the there's no real "sacrifice" here. That being said, any sacrifice that doesn't guarantee a better (or at least equal) position isn't a sacrifice either, it's just "hope chess", aka a bad move. In Blitz or Bullet you can make the case for a "bad" sacrifice for positional complexity and putting time pressure on your opponent to make accurate defensive moves. In the Opera game, Black just played a poor game start to finish. Giving up the bishop for the knight, pushing the B pawn while the king wasn't castled.
	▲	le-mark 6 hours ago \| parent \| prev [-]
		I had two “brilliant” moves in one chess.com game today. One was a bishop sacrifice that would have led to mate in three. The other was a queenside castle that the engine wanted me to do sooner. I suck at chess, although I did see the bishop sacrifice as the right move. The engine rated me at 1500 for the game.