\documentclass[tikz,border=10pt]{standalone}
                        \IfFileExists{newpxtext.sty}{\usepackage{newpxtext,newpxmath}}{}
                        \linespread{1.10}
                        \usetikzlibrary{shapes}
                        \usetikzlibrary{arrows.meta}
                        \usepackage{graphicx}

                        \begin{document}

                        % TikZ code with built-in styling for game trees
% TikZ libraries required for game trees
\usetikzlibrary{shapes}
\usetikzlibrary{arrows.meta}

% Style settings for game tree formatting
\tikzset{
    every node/.append style={font=\sffamily\itshape},
    every text node part/.append style={align=center},
    node distance=1.5mm,
    thick
}

% Built-in macro definitions for game tree drawing
\newdimen\ndiam
\ndiam1.5mm
\newdimen\sqwidth
\sqwidth1.6mm
\newdimen\spx
\spx.7mm
\newdimen\spy
\spy.5mm
\newdimen\paydown
\paydown2.5ex
\newdimen\treethickn
\treethickn1.0pt
\definecolor{chancecolor}{RGB}{117,145,56}
\definecolor{playeronecolor}{RGB}{234,51,35}
\colorlet{playertwocolor}{blue}
\colorlet{playerthreecolor}{orange}
\colorlet{playerfourcolor}{purple}
\colorlet{playerfivecolor}{cyan}
\colorlet{playersixcolor}{magenta}

% Game tree content from /home/docs/checkouts/readthedocs.org/user_builds/gambitproject/checkouts/889/catalog/img/vonstengelforges2008/fig1.ef
\begin{tikzpicture}[scale=0.8
  , StealthFill/.tip={Stealth[line width=.7pt,inset=0pt,length=13pt,angle'=30]}]
% \draw [help lines, color=green] (-5,0) grid (5,-6);
\draw [line width=\treethickn,color=playertwocolor] (-6,-5.625) arc(90:270:0.375)
  -- (2,-6.375) arc(-90:90:0.375) -- cycle;
\draw [line width=\treethickn,color=playertwocolor] (-2,-7.625) arc(90:270:0.375)
  -- (6,-8.375) arc(-90:90:0.375) -- cycle;
%% player 1 name 1
\def\playerone{1}
%% player 2 name 2
\def\playertwo{2}
%% level -2.0 node 1 player 0
\def\playerzero{Chance}
\draw [line width=\treethickn] (0,2)
   ;
%% level 2.0 node 1 player 1 xshift -4.0 from -2.0,1 move 1/2~(\frac{1}{2})
\draw [line width=\treethickn,color=chancecolor] (-4,-2)
   -- (0,2);
\draw (-2,0) node[left,xshift=-1mm,color=chancecolor] {1/2~($\frac{1}{2}$)\strut};
%% level 6.0 node 1 xshift -2.0 from 2.0,1 move X_G
\draw [line width=\treethickn,color=playeronecolor] (-6,-6)
   -- (-4,-2);
\draw (-5,-4) node[left,xshift=-0.5mm,color=playeronecolor] {X$_G$\strut};
%% level 12.0 node 1 xshift -1.0 from 6.0,1 move l_X payoffs 4 10
\draw [line width=\treethickn,color=playertwocolor] (-7,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{4}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{10}\strut$}
   -- (-6,-6);
\draw (-6.5,-9) node[left,xshift=-0.5mm,color=playertwocolor] {l$_X$\strut};
%% level 12.0 node 2 xshift 1.0 from 6.0,1 move r_X payoffs 0 6
\draw [line width=\treethickn,color=playertwocolor] (-5,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{6}\strut$}
   -- (-6,-6);
\draw (-5.5,-9) node[right,xshift=0.5mm,color=playertwocolor] {r$_X$\strut};
%% level 8.0 node 1 xshift 2.0 from 2.0,1 move Y_G
\draw [line width=\treethickn,color=playeronecolor] (-2,-8)
   -- (-4,-2);
\draw (-3,-5) node[right,xshift=0.5mm,color=playeronecolor] {Y$_G$\strut};
%% level 12.0 node 3 xshift -1.0 from 8.0,1 move l_Y payoffs 4 10
\draw [line width=\treethickn,color=playertwocolor] (-3,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{4}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{10}\strut$}
   -- (-2,-8);
\draw (-2.5,-10) node[left,xshift=-0.5mm,color=playertwocolor] {l$_Y$\strut};
%% level 12.0 node 4 xshift 1.0 from 8.0,1 move r_Y payoffs 0 6
\draw [line width=\treethickn,color=playertwocolor] (-1,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{6}\strut$}
   -- (-2,-8);
\draw (-1.5,-10) node[right,xshift=0.5mm,color=playertwocolor] {r$_Y$\strut};
%% level 4.0 node 1 player 1 xshift 4.0 from -2.0,1 move 1/2~(\frac{1}{2})
\draw [line width=\treethickn,color=chancecolor] (4,-4)
   -- (0,2);
\draw (2,-1) node[right,xshift=1mm,color=chancecolor] {1/2~($\frac{1}{2}$)\strut};
%% level 6.0 node 2 xshift -2.0 from 4.0,1 move X_B
\draw [line width=\treethickn,color=playeronecolor] (2,-6)
   -- (4,-4);
\draw (3,-5) node[left,xshift=-0.5mm,color=playeronecolor] {X$_B$\strut};
%% level 12.0 node 5 xshift -1.0 from 6.0,2 move l_X payoffs 6 0
\draw [line width=\treethickn,color=playertwocolor] (1,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{6}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{0}\strut$}
   -- (2,-6);
\draw (1.5,-9) node[left,xshift=-0.5mm,color=playertwocolor] {l$_X$\strut};
%% level 12.0 node 6 xshift 1.0 from 6.0,2 move r_X payoffs 0 6
\draw [line width=\treethickn,color=playertwocolor] (3,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{6}\strut$}
   -- (2,-6);
\draw (2.5,-9) node[right,xshift=0.5mm,color=playertwocolor] {r$_X$\strut};
%% level 8.0 node 2 xshift 2.0 from 4.0,1 move X_G
\draw [line width=\treethickn,color=playeronecolor] (6,-8)
   -- (4,-4);
\draw (5,-6) node[right,xshift=0.5mm,color=playeronecolor] {X$_G$\strut};
%% level 12.0 node 7 xshift -1.0 from 8.0,2 move l_Y payoffs 6 0
\draw [line width=\treethickn,color=playertwocolor] (5,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{6}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{0}\strut$}
   -- (6,-8);
\draw (5.5,-10) node[left,xshift=-0.5mm,color=playertwocolor] {l$_Y$\strut};
%% level 12.0 node 8 xshift 1.0 from 8.0,2 move r_Y payoffs 0 6
\draw [line width=\treethickn,color=playertwocolor] (7,-12)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{6}\strut$}
   -- (6,-8);
\draw (6.5,-10) node[right,xshift=0.5mm,color=playertwocolor] {r$_Y$\strut};
%% iset 6.0,1 6.0,2 player 2
%% iset 8.0,1 8.0,2 player 2
\node[inner sep=0pt,minimum size=\sqwidth,draw=chancecolor,fill=chancecolor,shape=rectangle] at (0,2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (-4,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (-6,-6) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (-2,-8) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (4,-4) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (2,-6) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (6,-8) {};

% Player color legend
\begin{scope}[scale=1,shift={(-8.5,2.0)}]
\node[inner sep=0pt,minimum size=\sqwidth,draw=chancecolor,fill=chancecolor,shape=rectangle] at (0,0) {};
\node[anchor=west] at (0.3,0) {Chance};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (0,-0.625) {};
\node[anchor=west] at (0.3,-0.625) {1};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (0,-1.25) {};
\node[anchor=west] at (0.3,-1.25) {2};
\end{scope}

\end{tikzpicture}

                        \end{document}