Loom

The first PC game FlameRider actually owned, and completed.  Great fun, and definitely worth doing on higher difficulty levels.  To clarify, much of the music comes from Swan Lake.

After a dozen years, five of them working in the industry, *still* a unique game mechanic - MoonShadow

Weelll... Zelda: Ocarina Of Time had you play musical notes, and if the first six corresponded to those of a spell you'd learned, you'd cast that spell. Which is pretty similar. Zelda was a slightly different style of game, though. --AC

Although not musical, AsheronsCall? also stole much of the mechanic.  (Though they later relented and went with sane spell lists.)  --Vitenka

Dungeon Master cast spells that way - with syllables in place of notes - three years before Loom.  You didn't have to learn the syllables first, though. --SGB

Oh good point - Ultima started that, I think.  --VasCorpPor??

"stole much of the mechanic" - casting spells you learned and intuited the meaning of by watching things happening, as the sole way of affecting the game environment? - MoonShadow

Ok, it didn't steal the good bit (learning from the environment) - it did steal the learning a chord sequence bit.  (You got hints as to which candles you needed, but no hint site could just tell you because it was randomised per person - but your easy spells (one candle each) gave you hints to build on.)  --Vitenka

Having (re)played it recently - the 'guess what verb you just learned' bit is mildly annoying, especially if you don't have the lovely in-box hint-filled stuff that came with the original edition.  Otherwise, I can't think of anything that is quite identical to it, but stand by all of the 'these are very similar' ones.  Oh, hard difficulty (not quite obvious which bits of staff play which notes, no hints as to which notes were played) is basically impossible for the tone-deaf.  Which is cruel.  --Vitenka

But given that the difficulty levels are only changing the musical skill required in the spellcasting, surely the tone-deaf just don't select hard difficulty level? --AC

As a recent addition, Aquaria uses 'singing' as a spell casting and affect your environment technique (and seems to be fairly central to the game) --K

Holy God, I remember that game!  I spent hours on it.  I particuarly liked how there was hidden content at the highest difficulty. --ElliottBelser