As you said in the description this was a very tough game, I couldn't even get past the third enemy!... until I realised that the player character's momentum persists after death, so what I did was go forward when I died so that when I respawned I could fly over the gap and onto that checkpoint before the long uphill path. It then took a lot of patience to slowly climb up to the end. Very rage gamey (maybe in a good way if that's what you were intending!) Controlling the weighty cube was certainly unique.