River Raid is an interesting game in a few ways. It was programmed by Carol Shaw, who is considered to be one of the first female game designers (or programmer, or both depending on where you get your information). It also featured massively long, non-repeating terrain, which was a pretty tough feat to accomplish on the marginal hardware of the Atari 2600.
But what was it? It was a shooting game (a.k.a. a Shoot ‘em Up, or Sh’mup) where you had to travel down a fictitious river, shooting down enemy ships, helicopters, planes, and bridges. You also had to keep an eye on your fuel gauge. Once it runs out, you = dead. So you have to make sure you hit the fuel tanks spaced throughout the river (which you can also shoot for points, natch). Your plane is pretty flimsy, it will crash if it takes a direct hit from anything but a fuel tank. Fuel tanks will give you gas. But, this is mitigated by the fact that the enemy vehicles and structures also become completely demolished with one shot.
Your goal, of course, is to get a high enough score to take a picture and send off for the super-sweet patch (the kind you sew on). I never managed to do that, though I did manage to destroy a bridge by hitting it with a plane. That counts for something, eh?