Hey, this is braingamer (from the stream). I played your game with my sister, and here are my thoughts:
This was a fun game. I like the teamwork aspect, where both players are critical to success. As more players are added they seem less relevant, as the inner two players really control the heart's movements. The outer ones only really protect from piranhas. If the pull strength of the cable was a little stronger in moving other players, I could see this being a great party game where everybody feels important.
The idea was really clever. Many team games are easier with more people, so the challenges are scaled up to match. In this one, more people bogs you down and makes it harder to coordinate - a neat application of the theme. As I mentioned earlier, I don't know that this really was borne out in the current version of the game. We tried a 6-player round (with each controlling 3) and it seemed considerably easier with more bodies to eat piranha hits. I concede that if those other characters were controlled by players with their own ideas then the game would be a little more challenging, but because the outer characters don't greatly affect the heart movement I doubt it would be significant.
The ravens are an interesting mechanic that I only really appreciated after trying with more characters. Good job keeping up the difficulty with more players that way.
Graphics look good. I like the shadow from the ravens passing overhead before they appear, and the splash effects from movement. Your gifs don't show the heart damage effects, so I was pleasantly surprised by that.
Music was fine, matched the feel of the game. A little short on the loop, but it's a game jam. Sound effects were generally good, though the cheer when you get a pearl was a little loud and started to grate after a while.
Overall, this game was a solid production. Neat mechanics and pretty fun to play. Looks like one I'll have to try with a group of friends.