I was able to replicate it, it seems consistant, could be that the editor allows a higher framerate than the WebGL player?
(My game speed is 6)
Don't worry about beating the game completely, we didn't have time to make the end, it just keeps getting harder until you run out of health (i'm going to put it in the game description because it's obviously not clear enough). And we decided last minute to scrap the energy bar because it felt unnecessary with the shield color changing.