Combat is a hell of a paradox nowadays: back when it came out -- as it was THE very first cartridge for the Atari 2600 -- it was simply amazing for several reasons (which I'll get to), but nowadays, due to how incredibly common it is (which if you pay anything over .50 for it -- if you hypothetically even need
it, lets say -- then you're playing too much for it), most people don't want to touch it with a 20 foot tank turret...yet, chances are, they'd still have fun with it.
Back when it was released, the 2600 was a pretty astounding thing, as I've read posts on video game boards of recollections of how people would be crowded around the 2600 display with games of Air/Sea Battle going at Sears. So, with how boring a game A/S Battle seems to most of us nowadays, giving it's company, that's one of the things that made Combat a really incredible game...and it was the PACK-IN, no less!
Another thing that made Combat pretty killer was that some of it very closely resembled the arcade game Tank, pitting two players against each other as tanks in a maze, hunting the other person down. However, not only was this not exactly a port of that game, but it actually surpassed Tank by having several tank game variations and battles in the air as well, requiring different strategies, controls, and technique to repeatedly blow a friend (or soon to be enemy) away. So Combat really met, and exceeded, any arcade game's expectations with all it's variations, rather than just the one game that the Tank coin-op provided.
And speaking of which, the tank variations pitted you against another player's tank in a maze to see who could shoot the other the most during it's two minute, 16 second timed game (dunno why we're given that strange time limit, but then this came out during the 70s, which Tiny Tim was also popular, as well as bell-bottom jeans and the brief disco explosion, so there). There are variations with regular shell shots, bullets that bounce around mazes (the best!) and invisible tanks, so you can take your pick, whatever fits your fancy (or "tops your tank", I guess you could say).
Then there's the biplane/air battle versions, which the planes fly fairly slow and their shots don't travel very far, although the have rapid-fire machine gun shots to make up for their short range. There are also variations for jet planes, which fly much quicker but only fire one shot, but that shot will travel a lot further, as well as one giant biplane against three smaller planes (that are all controlled and move at the same time) or two against two (which there's also a jet variation of two fighters being controlled at once [per player] as well).
Obviously, there's plenty to keep people busy with this one, and the perfect control, fairly decent sound effects, and mixed graphics also help (the jet fighters and tanks look cool, but the biplanes and those SQUARE clouds? Bah HA HA HA HA! Yes, when I look up at the sky at clouds in real life, squares are the first thing that come to my mind!).
The above would probably earn this game a 9 or a 10 out of 10 back in the day, but of course, this isn't still the 70s! So most of us don't even THINK of this game much (except for the five to six copies a lot of us 2600 owners have, grumble grumble). Also, all of the games are two players only, which can be limited at times when you're a player short, and the controls also change per game scenario: they're different whether you're playing the tank games, change when you move to a biplane variation, and they differ again when you're flying a jet. So you have to relearn them every time.
Still, this got plenty of play in everyone's Atari...yet I'll bet that nowadays people who scoff at video games would whine about it's violence, even though no one "dies" and there's no blood or anything.
How times change.