It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

1. you need to add steam-run in your configuration.nix (see nixos wiki about steam)
2. change file: "" and "":
- export LD_LIBRARY_PATH=./lib64

(- means remove, + means add instead)
This solves problem: "./dontstarve: error while loading shared libraries: cannot open shared object file: No such file or directory"