Atari 2600 was home to the first true action adventure game. And boy, was it amazing. With graphics more stylised than Wind Waker and a plot that genuinely has fewer holes than Heavy Rain's, it's a gaming classic and no mistake. Not that any of us would play it today. It's no Ico.
But it is also home to another gaming first - the secret room. Wait... how did you know I was going to say that? Anyway, it holds nought but a credit for the game's creator, Warren Robinett.
Above: Don't worry, your browser hasn't crashed - this is what games looked like in 1979
It may have been the first secret room to name the developer, but it certainly wan't the last. Indeed, Quake 2's secret room is pretty much identical in concept to Adventure's, it just has more concubines.
Fact is, though, this secret room was born out of necessity, or at least necessity for a creative mind with even a normal-sized ego. With rules at the time forbidding programmers to list their name in the game itself, Warren decided to break the rules... but hide his credit.
So on one grey background, you'll find there's a single grey dot. It seems insignificant in the Adventure game world, but you can pick it up and carry it. Taking it to the screen south-east of the Gold castle causes the wall on the right-hand side to blink - this is due to a hardware limitation that makes sprites blink when there are too many on the screen. This blinking temporarily switches the collision detection on and off, allowing you to pass through... and there it is. The secret room. Awesome.
How secret is it?
Secret enough that it got by the QA testers at Atari, but not so secret that an 11-year-old boy couldn't find it during normal play... Hey! Stop eating the grey pixel!
How roomy is it?
Well, it's actually an area outside of the castle, so not terribly room-like. That said, it's a single-screen with barriers you can't traverse so... good enough.
2. Legend of Zelda: A Link to the Past
There was a magazine competition in Nintendo Power back in the day, which had a modestly attractive prize. Your name in the next Zelda game. By modestly attractive, I mean freakin' amazing, of course and the lucky winner was one Chris Houlihan. There never was a more 'boy who plays Nintendo a lot and won a competition' name than that.
Trouble was, he did get his name in the game, but it was hidden so deep in the game's code, nobody ever knew about it. Until the internet came along, and with it software emulation that allowed hackers to tear into the game's code and discover the secret.
The way to trigger it in a regular copy of the game is to start the game afresh with the Pegasus boots equipped. Now, dash to the sewer entrance to the right of the castle. You'll fall down into the sewer... only it's not the sewer at all. It's Chris Houlihan's lost secret room! AND IT'S FULL OF RUPEES.
Above: We'd have wooted if we'd found all those Rupees. And if wooting had been invented in 1991
The room was removed from regular play in the GBA remake (although it's still there if you hack the ROM, apparently), meaning this particular secret room remains one of the coolest and most exclusive secrets in the Zelda universe. Tsk, I dunno - lucky kid gets his name in one of the greatest games ever made and all he did was enter a competition. I'd bet you anything we don't even get an honorary mention in Okamiden. Bah.
How secret is it?
Very. Dave H swears that he knew about it back in the 1990s, but I reckon he's just being contrary. Nobody was likely to find it during regular play. I mean, how many times do you start a game of LTTP with the thought 'I have to be in the sewers in 12 seconds' time!' We're not all as weird as Mr Garrison.
How roomy is it?
Above: Yep, that's a room alright. It's also very secret. Do we have a winner? Not quite...