Views
You will find them in
./app/views
The default skeleton comes with Haml, and we highly recommend it.
Nevertheless you can check the Sinatra documentation for a list of all the available templates.
Partials
Just specify the name of the partial you want to render and pass the local variables:
= partial :games, :players => @players
This will look for app/views/games.haml and the template will have access to the players local variable.