I absolutely love this gameplay mechanic. It felt incredible when I realised you could activate and deactivate your beam at will. The relief I felt upon getting to the fountain was incredibly satisfying.
At times I felt that the beam had absolutely hit the enemies, but it seemed to not kill them. I feel that making the beam collision slightly more forgiving could help improve the game, it just felt off when what seemed to me like an absolute hit passed right through them.
All in all, nice game!