It's not clear that the grid of green of orbs is harmful, they look a lot like collectibles. They also move in a way that makes it hard to gauge their height relative to the triangles. They could be saved for a later stage, because the core of the game is fun and addictive, but a little too hard to get into the flow of right away.
Some positive feedback sounds would be great, like when you Enter.
After clearing a stage it would be nice if the field was cleared, so you couldn't accidentally die when trying to Enter.
Many of my deaths happen immediately after Entering, when there aren't enough triangles below me due to random spawning.
It might be cool to add a drop button, kind of like Tetris, where you can slam your body into a triangle once you've lined it up.
The bar on the side is confusing and not something that I can pay attention to while playing, so I'm not sure what it means. It feels like the height indicator is backwards; it should move down when the player falls, not up, because you're being pulled down by gravity.
It's not immediately clear what the red and green triangles do. The green triangle spawning a hazard is confusing, usually green means good.
Really cool concept. I've always liked these "bounce higher" games but this is the first 3D one I've seen.