This is a recording of Greg Pascale's Invention in C# minor. Greg is my son - a college sophomore who plays electric guitar and dabbles in piano. He wrote this piece about year ago or so and it's not so easy to play. I finally got around to learning it - so we could see what it really sounded like other than through Sibelius robot-style playback.

Bach's inventions (who created them and was the only composer of western history to write in this way seriously) created a bunch of rules that inventions must follow. The biggest one is that they take material from the cantus firmus and repeat it in the contrapuntal bass immediately after being introduced. It's very nice and would work well under these conditions, it would be interested to hear it as a true invention.

A pleasing piece of work, and very well executed. Not so easy indeed, it seems to get quite ambitious in the middle section.
But I do not quite understand either what makes this an Invention. Perhaps Fantasy would be a better title - but what's in a name. I feel that it could have done with a secondary/contrasting theme though. Seems to me that many amateur compositions rely rather too much on one single idea.

Right. I think composing a piece out of a single idea is one of greatest challenges in music. Many amateurs go the tough way and try to write slow and lyrical pieces instead of short and joyful ones (which is of course not easy, either).

Not really the case here. In my opinion, your son did a very good job, Tom. Very moody and quite dark, I enjoyed it. And I think the title makes sense. It isn't an invention in the sense of counterpoint, but in a romantic sense: maybe something like "reminiscences of an invention". At least, I hear some passages that imitate the sound of counterpoint a bit.

Very nice. I agree with the comments of this sounding like a pseudo invention. Its very cool in how it is able to somewhat resemble an invention but also mix some new sounding harmonies in.