Interesting idea but perhaps could have done with a focus on the simply getting to the end as I felt it was challenging enough without the timer. I managed to get to the second layer of blocks and carried a small one with me but when I switched worlds and fell to the ground I wasn't able to get back up because the block was stuck somewhere I couldn't now reach.
Perhaps just having one block you can move but that will also transition with you between worlds could give a bit of focus to how the player gets through the level. There's emphasis on memorising where the platforms are in the opposing world so this might give it some structure.
Good atmosphere and nice music in the presentation though.