Wednesday, March 13, 2019

Game 51: Adventure (VCS)

Buy Adventure and about 90 other Atari games in the Atari Vault on Steam:

Read the manual at AtariAge:

Developed by and surreptitiously credited to Warren Robinett, whose previous works at Atari included Slot Racers and BASIC Programming, Adventure has often been called the best game on the Atari 2600. I can’t really disagree with that. It would perform pretty well on CRPG Addict’s BDI index, even if it would score modestly on all three aspects independently, and does some neat system-defying tricks like the fog-shrouded maze and persisting a game state across multiple screens. It’s still a pretty humble game without much replay value.

Here I am replaying it anyway, for one simple reason: I never beat game mode 3, which features the complete game world and randomizes the placement of the objects.

And since I’m replaying on the hardest game mode, I figured, why not flip the difficulty switches up while I’m at it? The switches affect dragon behavior. With both up, the dragons will snap their jaws shut much faster when they come in contact with you, and will flee from the sword.

The second change potentially makes a big difference in how the game is played. Normally, once you find the sword, you can search for and destroy the dragons, provided the bat doesn’t snatch the sword from you. Once you’ve killed three of them, you’re safe to explore the game, with nothing but the annoying bat to impede your progress. Once the dragons flee from you, they are nearly impossible to kill, and may be guarding rooms or items. The sword is the only thing that keeps the dragons away from you, and thanks to the bat you never know where it might have stashed the sword when you need it, or when it might snatch the sword from you.

In my playthrough, I managed to kill a dragon by accident, and didn’t encounter any more until I found the chalice room. At this point, I was able to drive the dragon away with the sword, swap it for the chalice, and then retreat to the yellow castle victorious. The bat proved a bigger nuisance, more than once stealing the item I needed and eventually dropping it off far away.

I found that this does have some data behind it worth analyzing. Dragons and bats behave by wandering around until they encounter a room with an object they like or dislike. When passing the edge of a screen they will end up in the next room over, same as when you pass the edge of the screen, but they ignore walls. This behavior occurs constantly, even when you aren’t in the same room with them. Consequently, every room in the game has four exits, even on edges that look like solid walls, because the bats and dragons can always exit a room through any edge.

Once in a room with an object they care about, they check the table for the highest row that applies, and approach it or run away from it accordingly.

Curiously, the yellow dragon is afraid of the yellow key. Perhaps a coding error that Robinett kept because he found it amusing?

To interpret the table, the topmost rows have the highest priority. In rows where a dragon is in the right column, the dragon is afraid of the object in the left column. In rows where a dragon is in the left column, the dragon likes the object in the right column.

Sword Red Dragon
Red dragon Player
Red dragon Chalice
Red dragon White key
Sword Yellow dragon
Yellow key Yellow dragon
Yellow dragon Player
Yellow dragon Chalice
Sword Green dragon
Green dragon Player
Green dragon Chalice
Green dragon Bridge
Green dragon Magnet
Green dragon Black key

In ordinary language, this means the dragons all flee from the sword (with ‘A’ difficulty – otherwise they ignore it). If they aren’t fleeing, then they pursue their favorite object on the screen, which may very well be you. All dragons have you as their top priority, and have the chalice as their second priority. After that, they vary, with the red dragon inclined to guard the white key, the yellow dragon inclined to run away from the yellow key, and the green dragon inclined to guard pretty much anything it finds.

So suppose you are the red dragon. You start off in a random room, and nothing's in it, so you just wander off in a straight line, going wherever the room edges will take you. Eventually you stumble on a room with the black key, but according to the table you're not interested in the black key, so you keep moving. Eventually you find the chalice room, so you move toward the chalice, and when you touch it, you stop in your tracks, content to guard it. Five minutes later, the player enters the room. Because you're more interested in the player than the chalice, you abandon the chalice and chase the player. But after the player exits the room, the chalice is now the only thing in the room with you, so you return to the chalice. Later, the player brings a sword into the room. The sword is higher on the list than the player, but you're programmed to move away from the sword, so you do, fleeing the room. There's nothing of interest in the next room so you keep moving in the same direction until you enter a room with something interesting.

The bat’s logic is different. It only likes one object at a time, but has ADHD and constantly changes its mind about the thing it wants. This is the table used:

Bat Chalice
Bat Sword
Bat Bridge
Bat Yellow key
Bat White key
Bat Black key
Bat Red dragon
Bat Yellow dragon
Bat Green dragon
Bat Magnet

It starts off interested in the chalice. After a certain amount of time, regardless of whether it found the chalice or not, the bat will lose interest in it and desire the sword instead. If it enters the room with the sword before changing its mind again, it will move toward the sword, pick it up, drop anything it happened to be carrying, and will then continue flying in the same direction for a while. Eventually it will move onto the bridge, then the yellow key, and so on until it loops back to the start of the list.

That said, I have never seen the bat swipe the chalice before I've found it myself, so there must some logic preventing this from happening. Theoretically it could swipe the chalice almost immediately, fly around a bit, then get bored, seek out the sword, find it in your hands, and steal it, dropping the chalice in its place. But I have never seen that happen. Anyone know how this works?


  1. One of my all time faves on the 2600... I remember being told that there was a secret "dot" you could find and how to use it to find Warren Robinett's signature.

    It never occurred to me that the catacombs are the same as the other screens until I saw a review with the full "illuminated" catacombs years later. It's really amazing that such a simple game could keep us occupied for so long, and that something as incredibly primitive as the 2600 could be programmed to pull it off.

  2. Nice article with some technical analysis.

    I believe the bat has stolen the chalice from me in the past. I have also seen the bat slay dragons by trying to swap the sword for the dragon itself! Ha ha!
    Adventure was not a linear quest but more of a mini-fantasy playground where lots could happen if you stuck around.

    I so love that game I created a tribute post to it here:


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