Contra (NES, 1987)
Contra put players in the sweaty boots and unfortunately-colored pants of Bill and Lance, who might as well be Arnold Schwarzenegger and Sylvester Stallone. Level design went from the backdrop of Predator's jungle to the HP Lovecraft-like organic interior of Alien. And it was a two player title.
Two player games weren't a novelty when Contra was released in 1987. You could play Combat or Maze Craze on your Atari 2600, but they were competitive. You could even play Super Mario Bros. or Commando on your NES, but they were alternating. Contra allowed both players to play both simultaneously and cooperatively and it was all the better for it. Your decisions could cost the other player their life, and you needed them to survive, especially if you were going through the game stock-style, without the Konami code. Here are some highlights, in order, from a typical conversation during a play-through of Contra:
"Can I get the spread shot?"
"Ugh. I got the stupid laser"
"Wait for me. Don't jump up, I'm still at the bottom. Don't jump-- Ugh. You just killed me!"
"I wanted the spread shot. You got it last time!"
"Stop stealing my lives."
"Get to the chopper!"
The Gentleman's Laser
We all stuck with the machine gun and spread shot for most of our play-throughs, but there was variety in the Contra arsenal. The laser wasn't for button mashers or NES Advantage users. It was a weapon for the calculating, patient player and, boy howdy, did laser dedication ever pay off. If you ever wanted to shoot a lightsaber out of Bill's barrel, this was your jam. It cut through enemies with ease and could eat away at boss health rather quickly. It made for a different play style than the usual run and gun days of yore.
The NES Advantage
This turned the default rifle into a more-desirable-than-the-actual-machine-gun rapid fire white bullet nightmare for those exploding bipedal aliens. Just wait until you light that bad boy up with the spread shot. You're unstoppable. Well, unless your buddy transcends the waterfall level too quickly.
If any game level was an experiment in the attention span of a kid, this was it. It was so difficult to be mindful of the other player and traverse that mortar-filled, boulder avalanche-filled environment at the same time.
Get a Life
After your lives ran out, you could acquire some more in a sometimes slick, sometimes malicious thievery of the other player's lives, one A Button press at a time. The proper Contra etiquette was to ask before doing it. Don't pretend like you did it by accident or didn't do it at all. "What? I had another life." "No you didn't." If your friend was out of lives and still holding the controller, your lives will be at stake. If your friend stole one of your lives, you'd just hope he wouldn't die in two seconds and waste it, but if you stole his, you certainly know you'd make the most of that life, and if you didn't, it most certainly wasn't your fault.
Back in the 8 bit era, we didn't just play a game during the first few months of release. We played it for years. If you went to a friend's house and they had Contra, you popped that thing in, pulled it back out, blew on it, popped it back in, entered the Konami code and you beat that thing! It didn't matter how many times. It was FUN.