\documentclass{standalone}

\usepackage{tikz}
\usepackage{shapes}

\begin{document}
\begin{tikzpicture}
  \grid{6}{6}{(-2,-2)}

  \staircase{cyan}{(0,0)}

  \square{green}{(0,-1)}
  \square{green}{(1,-1)}
  \square{green}{(2,-1)}

  \square{magenta}{(-1,0)}
  \square{magenta}{(-1,1)}
  \square{magenta}{(-1,2)}

  \square{yellow}{(1,2)}
  \square{yellow}{(2,1)}

  \square{lightgray}{(0,3)}
  \square{lightgray}{(3,0)}
\end{tikzpicture}
\end{document}