Thanks for the feedback! Glad you thought it was cool. That's valid criticism, because there actually was a hit effect and sound but they were clearly too subtle (the player flashed red, instead of white like most would look for, and all it did was tint his sprite red instead of properly flash).
And I'm so glad you mentioned your experience with the mammoth. If you didn't I wouldn't have finally figured out what to do about it! I should have put an invincibility timer when you get hit, so you can't be hit more than once within about half a second. I had a week to figure that out but never did, so thank you for leaving this feedback.
And thanks for playing too!