Optics.  Worldcoin launched with advance notice/a pretty website/twitter, and all of that gave it a air of gravitas, possibly undeserved, that helped give it buzz and lots of hashing attention.  Royalcoin, if I recall correctly, launched with no forewarning and looked sort of hackneyed together -- it didn't stand out.

Frankly, every coin to launch with advance warning has drawn a lot of attention, but most have botched the launch one way or another -- Worldcoin got through the process pretty smooth.  It stands out as a fairly well managed PR event, by alt-coin standards at least.

Right now, in the sea of alt-coin launches, optics matter.