The ns_install_v1.exe file you have requested: Modifications / natural selection / v1x / Natural Selection 1.0 - 352kb is not available. Perhaps try browsing all files for the game Half-Life and upload any files you want to share or are missing. This is the only information we could locate:
Natural Selection is an action-strategy game for the PC. It is a "Half-life modification", which means it is written on top of the Half-life game engine.