2. Bubble Bobble

Item generation mechanism, vast assortment of items, Bubble Alphabet, game modes and codes, and ending conditions

Published & developed by Taito

Designed by Fukio Mitsuji

Reason for inclusion:

How could this one not be included? Possibly the most mysterious game ever produced for arcades, with the only likely exception being its sequel, Rainbow Islands. Lots of stuff about this game was only fully understood when someone finally disassembled the code a few years back.

The game:

Bubble Bobble's multiple layers of secret knowledge make it a game for wizards. A huge array of arcane trivia must be learned to exploit Bubble Bobble's many systems. Some of it is only now becoming commonly known.

First thing to know is that the arcade game has secret codes. That was almost unheard of at the time -- yet Bubble Bobble not only has them, it will tell the player about them in the right circumstances, and using one is required to see the game's real ending. The circumstances in question, however, are nearly obscene: a game must be played to level 20, 30 or 50 without dying in order to see one, and death is rather common in Bubble Bobble after the first few levels. Once on the proper level, the bonus item normally generated in the level will instead be a door to a secret room, containing huge score bonuses and the code printed on the background... but the code, itself, is written in code.

At first it just looks like background decoration of runic glyphs, but it's really a secret message from the developers. The secret is spilled on the ending screen, where the player is informed "But it was not a true end!" and the specialness of the glyphs is revealed. That is, if he won in two-player mode. Winning with only a single player in the game sends him back to a random level. D'oh!

One of the secret codes makes the doors that lead to the bonus levels appear regardless of lives lost, which is nice to know once the player's already figured out the code, I guess. Another code, when entered from the title screen in the machine's attract mode, puts the game into "Super" mode, which mixes up the enemies in the levels and is somewhat more difficult. But it is only in Super mode that the game can truly be won, by working through all 100 levels again and finishing up in two-player mode. (And without dying, incidentally, but fortunately most people who win actually play as one player through most of the game, only putting player two in after the last boss has been beaten, and having just joined he won't have ever died.)

This is far from the only mysterious thing about the game. Probably the most mysterious is the formula that determines when special items appear. Most players believe it to be random, but actually they're all directly determined by the player's actions. The game maintains counts of a large array of trivia, like bubbles popped, times jumped, water bubbles burst, and times wrapped around the screen. When a counter exceeds a threshold value, a flag is set scheduling the item to be generated in an upcoming level.

The counts and flags are not reset when a game is finished, which is why new players often get treated to advanced items in the very first levels. But it also means if someone knows that, say, popping water bubbles makes level-skipping umbrellas appear more often, he can take advantage of that fact to skip ahead more often. Some of the tricks that make items appear cannot be done on every level, so it also tends to cause certain items to "clump," generating more often on particular boards.

It's nearly a textbook example of chaotic behavior in game design. The player's many varied actions lead, through unknown processes, to results that you'd assume are random, but seem to have some mysterious consistency to them. It is an interesting way to bring players into a game: to pin success on objects that appear almost on command, but without telling exactly what that command is.

Design lesson:

Pseudo-random numbers are used by many games, but Bubble Bobble, while apparently random, in fact contains few of them. Once their principles are understood they can be gamed, but they are not explained to the player. The result is that different play styles produce consistent variation in the game's response to them, which can provoke responses from players so complex that they border on superstition.

Links:

The Bubble Bobble mechanics discovered through source code examination are explicated at the Bubble Bobble Info Pages.