The series began with Castle of Dr. Brain. Here, the Featureless Protagonist is applying for an apprenticeship in Brain's laboratory. The entry exam consists of, well, reaching the laboratory, which is hidden deep inside the titular castle. Each step of the way is blocked by a puzzle or set of puzzles. The player must proceed through this linear maze, solving the wide variety of different puzzles in sequence, until the final puzzle lands the player in the laboratory. Puzzles in this game ranged from memorizing sounds and patterns, to jigsaw and word puzzles, and even rudimentary astronomy. It was also possible to change the difficulty of the puzzles, making it easier to finish the game if one or more puzzles proved very difficult. It also made the game accessible to both children and adults, who could experience roughly the same amount of challenge from what are essentially the same puzzles. Replay value was rather limited, though, due to all of the puzzle contents being the same every time and only completable once (on a particular difficulty level) before having to start over from the beginning.
In the second game, The Island of Dr. Brain, the protagonist is now Brain's apprentice and must travel to Dr. Brain's secret island to retrieve a massive battery, which is to be used to power Brain's newest contraption. Once again the island is a fairly-linear series of puzzles, each one requiring different skills to solve. Almost all puzzles in this game are either completely new or are advanced versions of the puzzles presented in the original game. For the most part, however, the Island is a more difficult game than its predecessor thanks to some truly devious puzzles. The use of a calculator can come in handy. In addition, the game keeps a scoring sheet of all puzzles solved within a single run. The game awards a gold "plaque" for solving puzzles on the highest difficulty, silver for medium, and bronze for easy. Also, unlike the first game, most of the puzzles are randomly generated and can be re-completed as many times as you want during a single game.
The third and fourth games (The Lost Mind of Dr. Brain and The Time-Warp of Dr. Brain, respectively) went in a slightly different direction. Instead of offering a linear path through various kinds of puzzles, gameplay was made more "casual", with all puzzles available for play at any time. You had to complete each puzzle repeatedly a certain number of times to "finish" one area of the game, and the end-game puzzle was unlocked only once all areas were finished. However, you could keep playing the puzzles over and over again, at varying difficulties, at any time. While certainly more repetitive than the earlier games, these sequels offered both a more open-ended experience as well as more content for players who enjoyed one or more puzzles and wanted to play them repeatedly. Unfortunately for the more cerebral crowd, a good portion of the puzzles in both games were practically arcade games more than they were any sort of puzzle or at all educational in nature. Needless to say, Corey Cole had nothing to do with either of these games.
Sometime after the fourth game was released, the rights to the Dr. Brain series were acquired by Knowledge Adventure, creators of the Jump Start series, and they released four more games: Dr. Brain Thinking Games: Puzzle Madness and IQ Adventure, Dr. Brain: Action Reaction, and The Adventures of Dr. Brain. The Knowledge Adventure games recast Dr. Brain as a twenty-something genius instead of a mad scientist in his sixties. The Thinking Games sub-series had less of an emphasis on educational content and focused more on solving puzzles, while Action Reaction is a straight-up first-person 3D platformer with a few puzzles thrown in.
The first two games, Castle of Dr. Brain and The Island of Dr. Brain were made for MS-DOS using 256-color VGA graphics, support for common sound cards, and shipped on floppy disks.
The third installment, The Lost Mind of Dr. Brain was released on a hybrid CD for Windows 3.1 and macOS and included digitized speech in place of text instructions, although the game would only work if the user manually set their display color-depth to 256 colors. The only files written to the user's hard drive were the saved games, requiring the CD to play the game.
All three games work perfectly under DOSBox (or Windows 3.1 under DOSBox in the case of the third game). Alternatively, ScummVM added support for the first two games.
Tropes in the series:
- Copy Protection: The "look up the manual to help solve a puzzle" variety for the first two games, and running the game entirely off the CD for the third game.
- Featureless Protagonist: No hints are ever given as to the player's identity. We just know they're good at solving puzzles.
- What's a Henway?: The final puzzle of the game, once you decode it, instructs you to "Pluck chicken (or was that a henway?)."
- Herding Mission: In one of the minigames in The Lost Mind of Dr. Brain, you are tasked with corralling cow-like neurotransmitters from one side of the brain to the other.
- Hints Are for Losers: Using the Hint System reduces your overall game score, and in the third game, it also reduces the value of the puzzles, requiring you to solve more of them.
- Knights and Knaves: The Programming Game in Castle requires you to deal with three robot heads, one of which always tells the truth (and will always follow your instructions), one of which always lies (and will always do the opposite of what you tell it to do), and one of which alternates (and will alternate between doing what you tell it and doing the opposite). Of course, the game doesn't tell you which is which. A similar minigame appears in the sequel, but there the cartridges are properly labeled.
- The Lab Rat: Rathbone in the third game.
- Mad Scientist: That's a no-Brainer!
- Mad Scientist's Beautiful Daughter: Well, beautiful niece, anyway, with Dr. Brain's niece Elaina, who appears in the third game.
- Magic Square Puzzle: Castle of Dr. Brain and Island of Dr. Brain have magic squares as one of the puzzles in each game. In the first game, the puzzle is the same every time you play (with a blank board), but the size will differ based on the difficulty. In the second game, you can replay the puzzle as many times as you like, and have it randomised each time.
- Playable Menu: The Time Warp of Dr. Brain has the Space Invaders section.
- Programming Game: Each game has one:
- Castle of Dr. Brain: A robot hand in a glass box to get three required items. Three heads with different behaviors are available to use (and must all be used on the harder difficulties).
- Island of Dr. Brain: A robot navigating a lab to collect crates for the player. Similar to Castle's heads, it has three cartridges available to use.
- The Lost Mind Of Dr. Brain: Motor Programming, Dr. Brain himself walking around in a maze and picking up brains. Harder difficulties offer additional subroutines to allow you to collect the additional brains in the maze.
- The Time-Warp of Dr. Brain: Gridlock, set up paths for cars.
- Shoo Out the Clowns: Ratbone is nowhere to be seen in the final section of Lost Mind, the brain stem.
- Shout-Out: Solving one puzzle in the observatory in Castle of Dr. Brain causes the monolith from 2001: A Space Odyssey to appear. Once you solve all the puzzles and get access to Dr. Brain's laboratory, a voice clip saying "My god, it's full of puzzles!" plays.
- Shout-Out to Shakespeare: In the third game, the Word Surge is set in a Shakespearian setting, where Rathbone, dressed in Shakespearian attire, quotes appropriate Shakespearean dialogue throughout."Alas, poor Yorick, the game begins anew. Come with and we shall be or not to be."
- Stock Puzzle