  Controlled variation of the electronic properties of 2D materials by applying
strain has emerged as a promising way to design materials for customized
applications. Using first principles density functional theory calculations, we
show that while the electronic structure and indirect band gap of
SnS$_\mathrm{2}$ do not change significantly with the number of layers, they
can be reversibly tuned by applying biaxial tensile (BT), biaxial compressive
(BC), and normal compressive (NC) strains. Mono to multilayered
SnS$_\mathrm{2}$ exhibit a reversible semiconductor to metal transition (S-M)
at strain values of 0.17, $-$0.26, and $-$0.24 under BT, BC, and NC strains,
respectively. Due to weaker interlayer coupling, the critical strain value
required to achieve S-M transition in SnS$_\text{2}$ under NC strain is much
higher than for MoS$_\mathrm{2}$. The S-M transition for BT, BC, and NC strains
is caused by the interaction between the S-$p_z$ and Sn-$s$, S-$p_x$/$p_y$ and
Sn-$s$, and S-$p_z$ and Sn-$s$ orbitals, respectively.
