During the mid 80s, the military genre was very popular in movies and television shows. On the tube, B.A. Barackus, Hannibal, and Faceman blew stuff up every week in The A-Team. In theaters, Stallone was Rambo in First Blood Part II, Arnie was simply a Commando, and Chuck Norris (before attaining internet omnipotence) headlined Delta Force. Video games, too, followed this trend, and the military themed Ikari Warriors was one example, featuring two player co-op.
You may be wondering what "Ikari" means. According to Wikipedia, it's Japanese for "anger". As you'd expect, the game features a couple warriors who appear to have anger issues, and they decide to take out their aggressions on the poor unfortunate enemies who oppose them. Foot soldiers, tanks, and even helicopters are barring the way for our short-tempered heroes, known as Ralf and Clark.
To say that Ralf and Clark are well armed is an understatement. Both semi and fully automatic machine guns were available, as were grenade launchers and even super grenades, all incredibly efficient at blowing stuff up. The action took place from an overhead perspective, and scrolled vertically. As the angry duo destroyed the bad guys, various power ups were dropped, but even these goodies don't reduce their anger one bit.
Two player co-op was one of the best features of the game. At the time, co-op wasn't very common, though it wasn't unheard of. Ikari Warriors was a good time when played solo, but of course, playing with a buddy made it just that much better (and easier). With two players, the playtime per quarter was a bit longer, meaning you might have enough leftover for some popcorn or a soda. Or better yet, more games.
Ikari Warriors was fairly innovative, though it might not seem that way from screenshots. The angry warriors had all sorts of weaponry, but their ammo was limited, and had to be managed accordingly. Ikari Warriors was one of the first games of its type that had such a mechanic, which added a bit of strategy to the game. Also unique was the ability for Ralf and Clark to walk into tiny tanks, emblazoned with a flashing "IN" sign. Once in the tank, the carnage could really start, since the heavy duty vehicles could run over some enemies without firing a single shot.
The most memorable part of the Ikari Warriors would have to be the rotary joysticks used in the control panel. The standard motion of the joystick controlled the players position on screen, allowing him move in eight directions. But the shaft of the joystick was also a control input, and could be twisted to control the direction your soldier faced. It took some getting used to, but it added a bit of realism to the gameplay that was exciting. There was no other control scheme like it on the market at the time, at least in my experience.
I've talked to many folks who still remember Ikari Warriors today, and the rotary joysticks are probably the biggest reason why. Unfortunately, most MAME cabinets don't use these joysticks, since they were used in so few games. Thus, the true Ikari Warriors experience isn't easily replicated. Several systems including the NES and the Atari 2600 got ports, but the facing-based shooting was missing from these as well.
Ikari Warriors is one of the few arcade games I'd really love to drop a roll of quarters into again today. I've not seen one in years; more's the pity. If you ever see an Ikari Warriors cabinet out in the wild, pop a few coins in, and if at all possible, get a friend to join you. It's certainly worth playing as a true co-op classic.