Hey! Pancho here, main developer of Nature's Call. Sorry for the late, we have just uploaded our game version for WebGL. Nevertheless it's an experimental version so we still recommend you to try the downloadable version if you can.
PS: I tried to made this build for mobile gaming too. The touch inputs are working fine, but at least in my Android there are serious graphics issues. But hey, you can try it to play on your phone too! Yeeeeiiiii.