The Power Of Two Ideas

THE best moves in chess have two ideas (three ideas are even better, but much rarer).
This applies whether the ideas are positional or tactical.
A simple example of the former applies on the very first move.

You are guaranteed to get this position as White (and as Black!)

White's moves 1.e4 and 1.g4 both have the idea of opening a diagonal for the light-square bishop, which is necessary to complete development.
But 1.e4 has another major idea - to fight for the centre.
Of course a bishop going to g2 fights for the centre, but then so does a bishop on d3, c4 or b5 (if it pressurises a black knight on c6 that also fights for the centre).
A move with two tactical ideas can be immediately devastating.
Spanton (1890) - Boris Litfin (1979)
Bad Wörishofen U2000 2019
Sicilian Accelerated Dragon
1.e4 c5 2.Nc3 g6 3.Nf3 Bg7 4.d4 cxd4 5.Nxd4 Nc6 6.Nxc6!?
An unusual move - 6.Be3 is normal - but the text has some tricky points.
6...bxc6 7.Bc4 Nf6?! 8.e5 Nd5??
8...Ng4!? 9.Qxg4 d5 10.Qf3 dxc4 11.Qxc6+ Bd7 is not completely clear, but probably favours White.
9.Nxd5 cxd5

White to play and win

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Not a difficult puzzle. White obviously captures the d5 pawn, but he has two ways to do it.
BL had somehow only considered 10.Bxd5?, which has the single tactical idea of hitting the a8 rook.
But I played 10.Qxd5, which hits the rook and has a second tactical idea, checkmate.
In some ways, finding moves that have two (or more) major ideas is what chess is mostly about.
A move with a single idea can usually be effectively countered - a player has to have a large advantage for a single-idea move to be really punishing.