Friend of mine said this song from Period Cube sounded a lot like Yiruma’s “River Flows in You”.

I checked it out, and yes it does. I intentionally played bits of “River Flows in You” a little out of order as some parts sound closer to the Period Cube song than others and I wanted to show the similar parts, but just playing straight through also works together. If you check the chord progression of the Period Cube song in that specific part, it’s the same as “River Flows in You”. The left hand of the Period Cube song in that part is also quite similar.