elem-grid_RBG_draw_lines+elem+3d+pgf+foreach.tex

% https://tex.stackexchange.com/a/271584/173708
% Modified by +arr for 7x7 plane, change paper size
% add comments

\documentclass[border={10}]{standalone}
\usepackage{tikz}  
\usepackage{tikz-3dplot} 

\tdplotsetmaincoords{60}{125} % view angles
\tdplotsetrotatedcoords{0}{0}{0} 

\begin{document}

\begin{tikzpicture}
    [%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        scale=5,tdplot_rotated_coords,
        grid/.style={very thin,gray}
    ]%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    %draw a grid in the x-y plane
    \foreach \x in {0,1,...,7}
        \foreach \y in {0,1,...,7} {
            \draw[grid] (\x,0) -- (\x,7);  % draw horizontal lines
            \draw[grid] (0,\y) -- (7,\y);  % draw vertical lines
        };
    % draw the color filled squares
    \draw[fill=blue]   (0,0,0) -- (0,1,0) -- (1,1,0) -- (1,0,0) -- cycle;
    \draw[fill=green]  (1,1,0) -- (2,1,0) -- (2,2,0) -- (1,2,0) -- cycle;

\end{tikzpicture}    
\end{document}