\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{decorations.pathreplacing,calligraphy}
\begin{document}
\begin{tikzpicture}
\draw[thick,stealth-stealth] (0,6.5) |- (6.5,0);
\draw foreach \x in {1,...,5} {(\x,0.1) -- (\x,-0.1) node[below]{$\x$}
(0.1,\x) -- (-0.1,\x) node[left]{$\x$}};
\draw[dashed] foreach \x in {1,3,5 }{(\x,0) |- (0,\x)};
\draw[red,thick] (3,3) -- (5,5);
\draw[thick,decorate,decoration={calligraphic brace,raise=0.5ex}]
(3,3) -- node[above left=0.6ex,align=center,font=\sffamily]{Completed\\
Strategies}(5,5);
\end{tikzpicture}
\end{document}