Easy to build with an ESP8266 (Wemos, NodeMCU choose your flavor) just 4 buttons and a string of 4 neopixels.
Code in Arduino IDE
This is just the source code and schematics so you can build it in a plastic box, tin can or whatever.
Next week 3D printed box and stripboard layout.
End project looks like this:
Source code and schematics on my weblog:
http://lucstechblog.blogspot.com/2018/12/simon.html
Luc