When I was a kid my family's first computer was the 16K Atari 400, for which we got a cassette drive, and a few years later we upgraded to the 64K Atari 800XL and got a disk drive. We had a lot of great games on that, both on cartridge and on disk, but there were several events that came later which increased my game stock considerably. One of them was, in the now-defunct Camillus Mall a store opened that sold games for the Atari. Antic magazine also became easier to find and often included disks right in the issue. Another time, my dad managed to pick up a boxload of stuff for $20 that included an old Atari 800 (I don't think it worked), a color printer (we couldn't get it to work but the output from a partial test page was beautiful), and several games. Those games included some great classics on disk like Temple of Apshai (sort of a graphical Roguelike) and Zork, along with a few other one-offs I recall fondly. But also there were a couple of cartridges, one of which was River Raid.

River Raid is best remembered for its appearance on the Atari 2600, but the 800 version was far superior and more colorful. Activision was known for producing some great colorful games, by making the most of a trick the Atari could perform (more on that later). The object of the game is simple: Your low-flying strike plane is flying down a river valley filled with enemy ships, helicopters, balloons, and more, and you have to navigate the river without bumping into the banks or the enemy craft, kill as many of the enemy as possible, and destroy a bridge at the end of each stage. The Atari 800 version also includes tanks, some of which will shoot at you from the riverbank, others which try to cross the bridge and will shoot at you if you don't get to them in time (or if you hit the bridge before they cross). Fuel barges could also serve as targets, and would keep up your fuel reserves so you could continue flying. This game is widely considered to be the best 8-bit scrolling shooter of its day.

The Atari had very limited graphics. It could display up to 8 colors, 4 of which were background graphics and 4 others for "players" using its player-missile graphics system. In that system, each player was a vertical strip, 8 pixels wide, that could be positioned along the horizontal axis. To move a sprite up and down, you had to wait for the vertical refresh interrupt (every 1/60 of a second when the TV's electron beam would return to its original position) and then move the sprite's data up or down. There were 4 players, and 4 missiles which were literally 2-bit versions of the players. Any of the above could be positioned independently, and they could be stretched to 2× or 4× width if desired.

Activision had a neat trick that they liked to use for getting around the Atari's graphical limitations, and they used it often. After each line of the display, they could use the TV's horizontal refresh interval to change the colors of the graphics mode and the players and missiles, and the positions of the players. In River Raid, no two enemies shared the same horizontal strip at the same time (except for those tanks on the side), so one player could be used for all the enemies at once. And because of the color trick, the normally single-color players had multiple colors. The result was amazing.

But even more amazing was that all this fit on an 8K cartridge. That's program code, sprites (facing left and right), the colors used for each kind of sprite, etc. In this game, it would have been impossible to do any level planning--so no one did. The only nod to level planning I've seen is that some enemies become more frequent in later levels, and of course the river tends to get narrower and trickier as well.

The game's designer was Carol Shaw, one of the first female programmers. At the time she wanted to make a space game, but Activision thought the market was saturated with those, so she made a river game instead. Her solution to the problem of having no room for levels was to use a pseudorandom number generator. Given a seed like the level number, it could generate a map with several different "blocks", break those up further and generate enemies, and then randomize the river banks a bit to make them ragged. You would have to play a long, long time to ever see a level repeat.

All of my games released on BYOND so far have also used dynamic content. Clever level design is challenging and can make a good game, but it also has the down side of reducing gameplay value, increasing production time, and even making the game end sooner than it has to. A good level generator, on the other hand, may require extra thought to work out but will reap huge benefits in keeping players interested.