  We report electron doping effects by Ni in
K$_{x}$Fe$_{2-\delta-y}$Ni$_{y}$Se$_{2}$ (0.06 $\leq$ $y$ $\leq$ 1.44) single
crystal alloys. A rich ground state phase diagram is observed. Small amount of
Ni ($\sim$ 4\%) suppressed superconductivity below 1.8 K, inducing insulating
spin glass magnetic ground state for higher Ni content. With further Ni
substitution, metallic resistivity is restored. For high Ni concentration in
the lattice the unit cell symmetry is high symmetry $I4/mmm$ with no phase
separation whereas both $I4/m + I4/mmm$ space groups were detected in the phase
separated crystals when concentration of Ni $<$ Fe. The absence of
superconductivity coincides with the absence of crystalline Fe vacancy order.
