\documentclass[a4paper,11pt]{article}
\usepackage{graphicx,amssymb,url,multicol}
\usepackage[usenames]{color}

\usepackage[top=2cm, bottom=2cm, left=2cm, right=2cm]{geometry} 
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\makeatletter
\usepackage{tikz}
\usepackage{pgfgantt}
\usepackage{pdflscape}
% reduce spacing in lists
\renewenvironment{enumerate}%
{\begin{list}{\arabic{enumi}.}%
{\leftmargin=1.5em\topsep=6pt\itemsep=4pt\parsep=0in\partopsep=0in\usecounter{enumi}}%
}{\end{list}}

\renewenvironment{itemize}%
{\begin{list}{--}%
{\leftmargin=1em\topsep=6pt\itemsep=4pt\parsep=0in\partopsep=0in}%
}{\end{list}}

% to add coloured comments
\newcommand{\comment}[1]{{\color{red} \marginpar{$\bigstar$} \textsf{[#1]}}}

\begin{document}
\title{\bf MyProject: Workplan
\vspace*{-2.2cm}}
\date{~}
\maketitle

\thispagestyle{empty}

\begin{figure*}[!h]
\centering
\hspace*{-0.4cm}
\begin{tikzpicture}[x=0.8cm,y=0.5cm]
\begin{ganttchart}[vgrid, 
hgrid,
title={draw=none, fill=black},
milestone label font=\normalsize,
milestone width=.3,
bar={fill=black},
bar height=.1,
%bar top shift=.19,
title label font=\bfseries\color{white},
%bar label font=\sffamily,
%milestone label font=\sffamily,
title label anchor={below=-1.6ex}, 
title left shift=.05, 
title right shift=-.05, 
title height=.8]{16} 
\gantttitle{\footnotesize year 1}{4}
\gantttitle{\footnotesize year 2}{4}
\gantttitle{\footnotesize year 3}{4}
\gantttitle{\footnotesize year 4}{4} \\
%\gantttitlelist{1,...,12}{}
%\gantttitlelist{1,...,12}{}
%\gantttitlelist{1,...,12}{}
%\gantttitlelist{1,...,12}{} \\
\ganttbar{\footnotesize 1.1 (Task1)}{1}{4} \\
\ganttbar{\footnotesize 1.2 (Task2)}{1}{4} \\
\ganttbar{\footnotesize1.3 (Task3)}{3}{6} \\
\ganttbar{\footnotesize 2.1 (Task4)}{3}{8} \\
\ganttbar{\footnotesize 2.2 (Task5)}{3}{8} \\
\ganttbar{\footnotesize 3.1 (Task6)}{5}{10} \\
\ganttbar{\footnotesize 3.2 (Task7)}{11}{16} \\
\ganttbar{\footnotesize 4 (Task8)}{7}{10} \\
\ganttbar{\footnotesize 5 (Task9)}{11}{16} \\
\ganttbar{\footnotesize 6.1 (Task10)}{3}{10} \\
\ganttbar{\footnotesize 6.2 (Task11)}{9}{16} \\
\ganttbar{\footnotesize 7 (Task12)}{1}{16} \\
\ganttmilestone{\footnotesize 8 (Task13)}{8}
\ganttmilestone{}{12}
\ganttmilestone{}{4}
\ganttmilestone{}{16}
\ganttlink[link mid=.7]{4}{2}{3}{4} 
\ganttlink[link mid=.4]{4}{3}{3}{4}

\ganttlink[link mid=.38]{6}{4}{3}{5} 
\ganttlink[link mid=.2]{6}{4}{3}{6} 
%\ganttlink[link mid=.14]{4}{3}{5}{6} 
\ganttlink[link mid=.4]{8}{6}{5}{7} 
\ganttlink[link mid=.4]{10}{7}{11}{8} 
\ganttlink[link mid=.4]{10}{9}{11}{10} 
\end{ganttchart}
\end{tikzpicture}
%\caption{...}
%\vspace*{0.1cm}
\end{figure*}
\end{document}