Cabal (Capcom, 1988) was always a bit overshadowed by Operation Wolf, but I still thought it was pretty cool for its time.
Originally an arcade game, it was later ported for the Amiga, C64, Atari ST, NES, Amstrad CPC, Sinclair ZX Spectrum and PCs.
The mission and gameplay is pretty clear and straight forward: Kill everything until you reach the final boss. Kill him too. The end.
The game itself was total carnage, you literally shot everything, from soldiers to tanks to buildings (which could be destroyed), and threw in the occasional grenade. The sound effects, the typical 80s "kill em all" kinda music, it was a blast. Playing this as a kid was simply nothing but fun.
I know it looks rather one-dimensional today and quite dated, but it still kicks ass, especially in the 2 player mode.