Loved the rad mechanic it makes for interesting gameplay. Also the game is well polished from the UI to the character animations. Only small downside is I think the combat start to become a bit too long after health increased but this is just a matter of tweaking.
I think you could exploit the radiation mechanic even more :D (like putting some non linear evolution to push the player to try and reach high level of radiation or something like that).
Overall great experience which could become a really interesting game with some more content! Keep it up