oneko 
The ever popular kitty-that-follows-your-mouse-pointer toy.
Neko is Japanese for cat. According to Wikipedia it was originally written for the NEC PC-9801.
There are many many versions. Generally it is considered Public Domain software, so I am placing my fork under the Unlicense.
This fork is based on Werner Randelshofer’s Java port.
The image files are ancient public domain. The Java code for v.1.0 is (c) 2010 Werner Randelhofer. The Java code for v.2.0 (c) 2019 Gerald Reno