Tried taking this old Mac shareware game (Chiral, a clone of Amiga game Atomino) for a revisit. I always found it unwieldy as a kid, but it's actually rather easy when you just dump all the awful 4s. Sadly, it doesn't meaningfully get interesting or harder as levels go on.
Having reviewed footage, I believe Atomino is the better and more interesting game (mainly due to its piece queue actually being weighted correctly, and not having random items) but Chiral not requiring a clean board to finish does give it a more high-speed, twitchy flavour.