Spotted in new game.

I found Dr. Moog's 1954 schematic on a blackboard in the new game Outer Worlds. Recognized it even though I've never seen a schematic of a tube based one before. I think my first theremin was one of the 150-in-1 or 100-in-1 electronic kits from good old Radio Shack. It definitely gave me a good laugh. Took a simple "theremin schematic" search to find this place and I just had to share this "caught in the wild" shot.

That's hilarious, thanks for sharing! 

How do you know it's RM's schematic?  (To my shame, I wasn't even aware that he made tube Theremins.)

It's actually in the schematics section here Moog Theremin Design.  It's exactly the same except for making the text look handwritten. 
You can even see the same photocopy glitch on pin 4 of the power supply rectifier.

Thanks for the link!  Yes, I see the same printing glitch on the V4 rectifier plate in both images - totally great catch, UpshawUnderhill!

"I think my first theremin was one of the 150-in-1 or 100-in-1 electronic kits from good old Radio Shack."

As a child I got a couple of those kits second hand from the thrift shop and played with them some.  There was a crystal radio and such in the things you could build, but I don't remember anything like a Theremin circuit in the instructions - though it was long ago and these were the low end kits.  Ended up cannibalizing them for parts once I got a proper plastic breadboard.

I'm pretty sure you're right. But I found what it was. It wasn't a Theremin but a Cds controlled oscillator. "Light controlled electronic harp" a ridiculously simple one transistor oscillator with the Cds controlling the base bias. 
In fact my googling led me back to Thereminworld once again: http://www.thereminworld.com/Article/13859/diy-build-a-small-optical-theremin-with-popular-science-for
I built all 150 at least once or twice and it definitely led to my interest in electronics, computers and now even 3d modeling and printing.

"I'm pretty sure you're right. But I found what it was. It wasn't a Theremin but a Cds controlled oscillator. "Light controlled electronic harp" a ridiculously simple one transistor oscillator with the Cds controlling the base bias."  - UpshawUnderhill

I don't believe I dreamed it (it was perhaps 50 years ago, but my memories of it are clear (though, sadly, the clarity of a memory is often not an indication of its accuracy [LINK])) but I remember finding a single transistor & audio transformer oscillator circuit in some publication or other that would vary the oscillation rate depending on the series impedance in the supply, and I swear it could do polyphony by placing two or more series impedance elements in parallel (the elements may have been a mix of resistors and/or coils, I didn't really know what I was pulling out of my junk box back then, and I notoriously took everything I could get my hands on apart).  I put the oscillator in a box with 8 SPST pushbuttons, pressing one or more of the buttons would supply power as well as the series impedance, and pressing two or more would give multiple simultaneous tones.  Like most things I built back then it got cannibalized for the switches when the next project required them.