(To be clear, I am not the creator here.)
There are many things like this, but for what it is worth, this is a pretty well executed one: simple to use, elegant UX, produces pleasing tones even when used inexpertly.
Also the fact that this one expands to a large number of steps is somewhat unique I think. (BTW it seems odd to me that the lower bound on the number of steps is 10 rather than the conventional 8.)
I too have seen (and played with) a large number of step-sequencer things and literally have three of them sitting next to me on my desk while I type this.
But I still enjoyed playing with this one for a little while.
I'm sure the OP learned something from this exercise, and there could be people for whom this is their first/best experience with a simple step sequencer, so it may "unlock" something for someone. But I think that's unnecessary "gravy" in this case. Sometimes the "joy" of creating is reason enough to do it. I may never visit Music Grid again but I'm glad OP shared it.