You can access these apps directly on the web
If you want to run them locally, you'll need R with the shiny package.
library(shiny)
runGitHub("shinyApps",username="NicolasDurrande",subdir="GP_playground")
runGitHub("shinyApps",username="NicolasDurrande",subdir="catapult")
Have fun, any feedback is more than welcome!