There is only one file type that uses the .NEKO extension:
Neko Source Code File
Source code file written in Neko, a high-level dynamically typed programming language; can be compiled by the Neko compiler into bytecode that is run on the Neko virtual machine, similarly to how Java programs are compiled and then run on the Java Virtual Machine (JVM).
The Neko VM is available for Mac, Windows, and Linux platforms. Therefore, programs written in Neko can be compiled and run on any of these operating systems.
Updated: March 14, 2013