I totally agree with you regarding that directions point. I will try to make it more interactive in the next iteration of the game by adding some actual arrow key indications near or maybe the reactor itself. Yeah, that bubble thingy is actually the atoms inside the reactor :) . I wasn't able to convey that clearly to the player, that the energy is rising due to those bubble thingy collisions. XD
I will surely make the next iteration of this game better.
Thanks for taking the time to write out this review mate : )