\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/vonstengel2022/fig10.1.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] (-1.5,-7.125) arc(90:270:0.375)
  -- (4.5,-7.875) arc(-90:90:0.375) -- cycle;
%% player 1 name I
\def\playerone{I}
%% player 2 name II
\def\playertwo{II}
%% level -2.0 node 1 player 0
\def\playerzero{Chance}
\draw [line width=\treethickn] (0,2)
   ;
%% level 2.0 node 1 player 1 xshift -3.0 from -2.0,1 move 1/2~(\frac{1}{2})
\draw [line width=\treethickn,color=chancecolor] (-3,-2)
   -- (0,2);
\draw (-1.5,0) node[left,xshift=-1mm,color=chancecolor] {1/2~($\frac{1}{2}$)\strut};
%% level 6.0 node 1 xshift -1.5 from 2.0,1 move T payoffs 0 16
\draw [line width=\treethickn,color=playeronecolor] (-4.5,-6)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{16}\strut$}
   -- (-3,-2);
\draw (-3.75,-4) node[left,xshift=-0.5mm,color=playeronecolor] {T\strut};
%% level 7.5 node 1 xshift 1.5 from 2.0,1 move B
\draw [line width=\treethickn,color=playeronecolor] (-1.5,-7.5)
   -- (-3,-2);
\draw (-2.25,-4.75) node[right,xshift=0.5mm,color=playeronecolor] {B\strut};
%% level 10.0 node 1 xshift -1.0 from 7.5,1 move a payoffs 12 4
\draw [line width=\treethickn,color=playertwocolor] (-2.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{12}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{4}\strut$}
   -- (-1.5,-7.5);
\draw (-2,-8.75) node[left,xshift=-0.5mm,color=playertwocolor] {a\strut};
%% level 10.0 node 2 xshift 1.0 from 7.5,1 move b payoffs -4 20
\draw [line width=\treethickn,color=playertwocolor] (-0.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{-4{\phantom-}}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{20}\strut$}
   -- (-1.5,-7.5);
\draw (-1,-8.75) node[right,xshift=0.5mm,color=playertwocolor] {b\strut};
%% level 3.5 node 1 player 1 xshift 3.0 from -2.0,1 move 1/2~(\frac{1}{2})
\draw [line width=\treethickn,color=chancecolor] (3,-3.5)
   -- (0,2);
\draw (1.5,-0.75) node[right,xshift=1mm,color=chancecolor] {1/2~($\frac{1}{2}$)\strut};
%% level 6.0 node 2 xshift -1.5 from 3.5,1 move C payoffs 0 16
\draw [line width=\treethickn,color=playeronecolor] (1.5,-6)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{16}\strut$}
   -- (3,-3.5);
\draw (2.25,-4.75) node[left,xshift=-0.5mm,color=playeronecolor] {C\strut};
%% level 7.5 node 2 xshift 1.5 from 3.5,1 move D
\draw [line width=\treethickn,color=playeronecolor] (4.5,-7.5)
   -- (3,-3.5);
\draw (3.75,-5.5) node[right,xshift=0.5mm,color=playeronecolor] {D\strut};
%% level 10.0 node 3 xshift -1.0 from 7.5,2 move a payoffs 12 4
\draw [line width=\treethickn,color=playertwocolor] (3.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{12}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{4}\strut$}
   -- (4.5,-7.5);
\draw (4,-8.75) node[left,xshift=-0.5mm,color=playertwocolor] {a\strut};
%% level 10.0 node 4 xshift 1.0 from 7.5,2 move b payoffs 20 -4
\draw [line width=\treethickn,color=playertwocolor] (5.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{20}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{-4{\phantom-}}\strut$}
   -- (4.5,-7.5);
\draw (5,-8.75) node[right,xshift=0.5mm,color=playertwocolor] {b\strut};
%% iset 7.5,1 7.5,2 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 (-3,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (-1.5,-7.5) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (3,-3.5) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (4.5,-7.5) {};

% Player color legend
\begin{scope}[scale=1,shift={(-6.0,2.0)}]
\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) {I};
\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) {II};
\end{scope}

\end{tikzpicture}

                        \end{document}