Thanks for taking the time to play the game and provide feedback!
The room that you are describing with the big circle is the only puzzle in the level. There is a block on top of a platform. You use the tractor beam to pull that block and then place it on the circular button. Then the gate opens.
You jump by pressing the left joystick.
I might rethink how I display the user's health.
It is frustrating to start over at the beginning when you die. The reason I don't have save points along the way is that I am not sure if the final game is going to have permadeath. I'm still planning on having short, randomly generated levels. That said, my original idea for the game was more ambitious where there was one massive level (Metroidvania) with save points, but at some point I started to feel that was unrealistic.
As for the floating cubes, Maybe they should look more menacing so it is clear that you aren't supposed to touch them.