\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{p1rgb}{RGB}{0,127,255}
\definecolor{p2rgb}{RGB}{221,121,224}

% Game tree content from /home/docs/checkouts/readthedocs.org/user_builds/gambitproject/checkouts/stable/catalog/journals/mor/vonstengelforges2008/fig1__Original_Layout.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,draw=none,color=p2rgb,fill=p2rgb,fill opacity=0.2] (-5.3,-3.625) arc(90:270:0.375)
  -- (-1.1,-4.375) arc(-90:90:0.375) -- cycle;
\draw [line width=\treethickn,draw=none,color=p2rgb,fill=p2rgb,fill opacity=0.2] (1.1,-3.625) arc(90:270:0.375)
  -- (5.3,-4.375) arc(-90:90:0.375) -- cycle;
%% % Extensive-form game transcribed from the provided figure.
%% % DrawTree .ef format.
%% % Layout is chosen to preserve the original geometry of the image:
%% % chance at the top, two Player 1 singleton information sets,
%% % crossed middle branches, and two horizontal Player 2 information sets.
%% %
%% % Player 0: Chance
%% % Player 1: 1
%% % Player 2: 2
%% %
%% % Chance chooses G or B with probability 1/2 each.
%% % Player 1 observes the chance outcome and chooses X or Y, with labels
%% % indexed by the realized chance outcome: X_G, Y_G, X_B, Y_B.
%% % Player 2 observes only whether the signal is X or Y, not the chance outcome.
%% player 0 name Chance
\def\playerzero{Chance}
%% player 1 name 1
\def\playerone{1}
%% player 2 name 2
\def\playertwo{2}
%% % Root chance node.
%% level 0 node n1 player 0
\draw [line width=\treethickn] (0,-0)
   ;
%% % Chance branches, arranged as in the figure.
%% level 2 node n2 xshift -2.8 from n1 move \frac{1}{2} player 1
\draw [line width=\treethickn,color=chancecolor] (-2.8,-2)
   -- (0,-0);
\draw (-1.4,-1) node[left,xshift=-1mm,color=chancecolor] {$\frac{1}{2}$\strut};
%% level 2 node n3 xshift 2.8 from n1 move \frac{1}{2} player 1
\draw [line width=\treethickn,color=chancecolor] (2.8,-2)
   -- (0,-0);
\draw (1.4,-1) node[right,xshift=1mm,color=chancecolor] {$\frac{1}{2}$\strut};
%% % Player 1 branches.
%% % Left Player 1 node: chance outcome G.
%% level 4 node n4 xshift -2.5 yshift -0.9 from n2 move X_G
% ----- Error: unknown keyword yshift
% ----- Error: unknown keyword -0.9
\draw [line width=\treethickn,color=p1rgb] (-5.3,-4)
   -- (-2.8,-2);
\draw (-4.05,-3) node[left,xshift=-0.5mm,color=p1rgb] {X$_G$\strut};
%% level 4 node n5 xshift 3.9 yshift -0.9 from n2 move Y_G
% ----- Error: unknown keyword yshift
% ----- Error: unknown keyword -0.9
\draw [line width=\treethickn,color=p1rgb] (1.1,-4)
   -- (-2.8,-2);
\draw (-0.85,-3) node[right,xshift=0.5mm,color=p1rgb] {Y$_G$\strut};
%% % Right Player 1 node: chance outcome B.
%% % The X_B and Y_G branches cross, matching the original layout.
%% level 4 node n6 xshift -3.9 yshift -0.9 from n3 move X_B
% ----- Error: unknown keyword yshift
% ----- Error: unknown keyword -0.9
\draw [line width=\treethickn,color=p1rgb] (-1.1,-4)
   -- (2.8,-2);
\draw (0.85,-3) node[left,xshift=-0.5mm,color=p1rgb] {X$_B$\strut};
%% level 4 node n7 xshift 2.5 yshift -0.9 from n3 move Y_B
% ----- Error: unknown keyword yshift
% ----- Error: unknown keyword -0.9
\draw [line width=\treethickn,color=p1rgb] (5.3,-4)
   -- (2.8,-2);
\draw (4.05,-3) node[right,xshift=0.5mm,color=p1rgb] {Y$_B$\strut};
%% % Player 2 information sets.
%% % X-signal information set: histories (G,X_G) and (B,X_B).
%% iset n4 n6 player 2
%% % Y-signal information set: histories (G,Y_G) and (B,Y_B).
%% iset n5 n7 player 2
%% % Player 2 actions and terminal payoffs, listed left-to-right as in the image.
%% % At the X-signal information set.
%% level 6 node n8 xshift -0.45 from n4 move l_X payoffs 4 10
\draw [line width=\treethickn,color=p2rgb] (-5.75,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{4}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{10}\strut$}
   -- (-5.3,-4);
\draw (-5.525,-5) node[left,xshift=-0.5mm,color=p2rgb] {l$_X$\strut};
%% level 6 node n9 xshift 0.45 from n4 move r_X payoffs 0 6
\draw [line width=\treethickn,color=p2rgb] (-4.85,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{6}\strut$}
   -- (-5.3,-4);
\draw (-5.075,-5) node[right,xshift=0.5mm,color=p2rgb] {r$_X$\strut};
%% level 6 node n10 xshift -0.45 from n6 move l_X payoffs 6 0
\draw [line width=\treethickn,color=p2rgb] (-1.55,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{6}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{0}\strut$}
   -- (-1.1,-4);
\draw (-1.325,-5) node[left,xshift=-0.5mm,color=p2rgb] {l$_X$\strut};
%% level 6 node n11 xshift 0.45 from n6 move r_X payoffs 0 6
\draw [line width=\treethickn,color=p2rgb] (-0.65,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{6}\strut$}
   -- (-1.1,-4);
\draw (-0.875,-5) node[right,xshift=0.5mm,color=p2rgb] {r$_X$\strut};
%% % At the Y-signal information set.
%% level 6 node n12 xshift -0.45 from n5 move l_Y payoffs 4 10
\draw [line width=\treethickn,color=p2rgb] (0.65,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{4}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{10}\strut$}
   -- (1.1,-4);
\draw (0.875,-5) node[left,xshift=-0.5mm,color=p2rgb] {l$_Y$\strut};
%% level 6 node n13 xshift 0.45 from n5 move r_Y payoffs 0 6
\draw [line width=\treethickn,color=p2rgb] (1.55,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{6}\strut$}
   -- (1.1,-4);
\draw (1.325,-5) node[right,xshift=0.5mm,color=p2rgb] {r$_Y$\strut};
%% level 6 node n14 xshift -0.45 from n7 move l_Y payoffs 6 0
\draw [line width=\treethickn,color=p2rgb] (4.85,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{6}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{0}\strut$}
   -- (5.3,-4);
\draw (5.075,-5) node[left,xshift=-0.5mm,color=p2rgb] {l$_Y$\strut};
%% level 6 node n15 xshift 0.45 from n7 move r_Y payoffs 0 6
\draw [line width=\treethickn,color=p2rgb] (5.75,-6)
   node[below,yshift=0.1\paydown,color=p1rgb] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=p2rgb] {$\mathsf{6}\strut$}
   -- (5.3,-4);
\draw (5.525,-5) node[right,xshift=0.5mm,color=p2rgb] {r$_Y$\strut};
\node[inner sep=0pt,minimum size=\sqwidth,draw=chancecolor,fill=chancecolor,shape=rectangle] at (0,-0) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p1rgb,fill=p1rgb,shape=circle] at (-2.8,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p1rgb,fill=p1rgb,shape=circle] at (2.8,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p2rgb,fill=p2rgb,shape=circle] at (-5.3,-4) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p2rgb,fill=p2rgb,shape=circle] at (1.1,-4) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p2rgb,fill=p2rgb,shape=circle] at (-1.1,-4) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=p2rgb,fill=p2rgb,shape=circle] at (5.3,-4) {};

% Player color legend
\begin{scope}[scale=1,shift={(-7.25,-0.0)}]
\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=p1rgb,fill=p1rgb,shape=circle] at (0,-0.625) {};
\node[anchor=west] at (0.3,-0.625) {1};
\node[inner sep=0pt,minimum size=\ndiam,draw=p2rgb,fill=p2rgb,shape=circle] at (0,-1.25) {};
\node[anchor=west] at (0.3,-1.25) {2};
\end{scope}

\end{tikzpicture}

                        \end{document}