Hey nice work here. I like environment setup, it does give me that post-apocalyptic feel.
I like the portal a lot at the end, really cool effects. I don't want to ruin the surprise but i also liked the secret thing you can do (not sure if it is meant to be a hidden mechanic, but i liked it as is).
Just for the feedback purpose, i feel like the jump needs more of a "stick to ground" force. it gives player more sense of control. As a player, i didn't feel like I was in control of the jump because you slide a bit when you land.
great work tho! keep it up!