\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/fig10.12.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=playeronecolor] (-1.5,-5.625) arc(90:270:0.375)
  -- (4.5,-6.375) 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 2 xshift -3.0 from -2.0,1 move 1/3~(\frac{1}{3})
\draw [line width=\treethickn,color=chancecolor] (-3,-2)
   -- (0,2);
\draw (-1.5,0) node[left,xshift=-1mm,color=chancecolor] {1/3~($\frac{1}{3}$)\strut};
%% level 10.0 node 1 xshift -1.5 from 2.0,1 move C payoffs 1 -1
\draw [line width=\treethickn,color=playertwocolor] (-4.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{1}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{-1{\phantom-}}\strut$}
   -- (-3,-2);
\draw (-3.75,-6) node[left,xshift=-0.5mm,color=playertwocolor] {C\strut};
%% level 6.0 node 1 xshift 1.5 from 2.0,1 move O
\draw [line width=\treethickn,color=playertwocolor] (-1.5,-6)
   -- (-3,-2);
\draw (-2.25,-4) node[right,xshift=0.5mm,color=playertwocolor] {O\strut};
%% level 10.0 node 2 xshift -1.0 from 6.0,1 move K payoffs 1 -1
\draw [line width=\treethickn,color=playeronecolor] (-2.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{1}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{-1{\phantom-}}\strut$}
   -- (-1.5,-6);
\draw (-2,-8) node[left,xshift=-0.5mm,color=playeronecolor] {K\strut};
%% level 10.0 node 3 xshift 1.0 from 6.0,1 move S payoffs 0 0
\draw [line width=\treethickn,color=playeronecolor] (-0.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{0}\strut$}
   -- (-1.5,-6);
\draw (-1,-8) node[right,xshift=0.5mm,color=playeronecolor] {S\strut};
%% level 2.0 node 2 player 2 xshift 3.0 from -2.0,1 move 2/3~(\frac{2}{3})
\draw [line width=\treethickn,color=chancecolor] (3,-2)
   -- (0,2);
\draw (1.5,0) node[right,xshift=1mm,color=chancecolor] {2/3~($\frac{2}{3}$)\strut};
%% level 10.0 node 4 xshift -1.5 from 2.0,2 move c payoffs 0 0
\draw [line width=\treethickn,color=playertwocolor] (1.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{0}\strut$}
   -- (3,-2);
\draw (2.25,-6) node[left,xshift=-0.5mm,color=playertwocolor] {c\strut};
%% level 6.0 node 2 xshift 1.5 from 2.0,2 move o
\draw [line width=\treethickn,color=playertwocolor] (4.5,-6)
   -- (3,-2);
\draw (3.75,-4) node[right,xshift=0.5mm,color=playertwocolor] {o\strut};
%% level 10.0 node 5 xshift -1.0 from 6.0,2 move K payoffs 0 0
\draw [line width=\treethickn,color=playeronecolor] (3.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{0}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{0}\strut$}
   -- (4.5,-6);
\draw (4,-8) node[left,xshift=-0.5mm,color=playeronecolor] {K\strut};
%% level 10.0 node 6 xshift 1.0 from 6.0,2 move S payoffs 1 -1
\draw [line width=\treethickn,color=playeronecolor] (5.5,-10)
   node[below,yshift=0.1\paydown,color=playeronecolor] {$\mathsf{1}\strut$}
   node[below,yshift=-0.9\paydown,color=playertwocolor] {$\mathsf{-1{\phantom-}}\strut$}
   -- (4.5,-6);
\draw (5,-8) node[right,xshift=0.5mm,color=playeronecolor] {S\strut};
%% iset 6.0,1 6.0,2 player 1
\node[inner sep=0pt,minimum size=\sqwidth,draw=chancecolor,fill=chancecolor,shape=rectangle] at (0,2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (-3,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (-1.5,-6) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playertwocolor,fill=playertwocolor,shape=circle] at (3,-2) {};
\node[inner sep=0pt,minimum size=\ndiam,draw=playeronecolor,fill=playeronecolor,shape=circle] at (4.5,-6) {};

% 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}