well you have rain, usual sounds. acid rain, harse sounding, touching on the ground. trust me when it comes to level design if you can tell a story with sound, find a sound designer to help with that, trigger things that can forgive poor graphics and layout. you can tell a story so much with sound. i've not seen many games for instance that use ASMR well. i'd love to see someone do that. maybe bigger than the scope of this game but worth exploring.