This felt pretty stressful to play... in a totally good way! I really like the idea that if you take too long to make a decision you miss that chance to decide anything at all. Can definitely see it being taken further with more options available - perhaps with character buffs and enemies with multiple targettable components - but I did appreciated the simplicity of the two mouse buttons in this case.

This might just be me, but I do think it needs to be a little more obvious when it's the player's turn - I kept wasting time looking to check before /then/ trying to think about what I wanted to do - a more-obvious change that you don't need to be focusing on might be better - maybe a change in background colour or glow or something.

But as a proof of contept this is very cool - and anything with penguins gets an automatic +1 from me!! Nice job!

I had to play the game because our game was also based on "Only one second" ^.^

I had difficulty at first understanding the timing of attack and healing. I was spamming the attack and healing as fast as I could. It took me a bit to understand you can only trigger one when the timer is blue. After than it became more clear and enjoyable :)

Also kudos for posting the source code! :)