A really nice-looking game with a cool concept. I liked the music too.
The first two times I lost, I was confused as to why. It said that I or my friend had died when we both still had plenty of health left; it felt like a bug. Only when I came back here and read some of the comments did I realise there's a timer. So I suspect that the time simply ran out, and that's what caused me to lose. I.e. perhaps have a dedicated lose screen for when the timer runs out. (Also, some feedback if the time is getting low would also have been welcome.)
Overall, this is a pretty good game, if a bit prone to becoming repetitive after a while. Nicely done.