You can spin your hand 180° around Y (index / up). Then Z (middle) points away from you, “forward”. And X (thumb) will point left.

Thus the “Left-Up-Forward” + Right-handed.

I don’t follow why that means I’m wrong.

“Was” here refers to their old Z-Up, left-handed coordinates, where X was forward, Y was right, and Z was up.

He references “Left-Up-Forward”, so X is Left, Z is into the screen.

2D is not a consideration, even if it’d be logical. (That’s where Left-handed Right-Up-Forward grows out of.)

You are wrong, @egerlach@lemmy.ca was correct:

[…] we’re transitioning to the Left-Up-Forward (LUF) coordinate system.

Source: https://forums.unrealengine.com/t/we-re-moving-to-the-left-up-forward-luf-coordinate-system/2540901