Mad scientist Youtuber grows a rat brain that is learning to play Doom

pcgamer.com:

Getting Doom running on things is a favourite pastime of the tech-inclined, with id's classic title now available on anything from pregnancy tests to potatoes. One of my favourites veered slightly off-tangent from that, being not about how to get Doom running but instead training rats called Carmack and Romero to play it.

Now Youtuber The Thought Emporium has gone one step further in an experiment that is alternately amazing, terrifying, and leads to deep philosophical thoughts about Cacodemons. The guy's got a bunch of lab-grown rat neurons that have somehow been trained to play Doom. 

The experiment uses cortical rat neurons, because of their affordability and because they can learn well enough for these purposes (you too can order a million frozen rat neurons online, what a world). Yes, you could use human neurons to the same end, and no doubt someone watching this video will be off to order some imminently, but they're expensive and almost seem overkill because playing Doom can be stripped-down to relatively simple yes / no patterns.

So The Thought Emporium more-or-less breaks down Doom as a top-down 2D game rather than 3D, because the 3D effect is visual rather than having any impact on actions in the game. Thus the neurons have to perform actions like moving forwards or back, rotating the character, firing and changing weapons. The neurons themselves are associated with an electrode array with 46 electrodes that they can somehow trigger in a way I frankly don't understand. But based on audio stimulus, which somehow spatially communicates the above elements of the game, they can trigger these electrodes in patterns.

The video details the process of growing the neurons, how they gradually form clusters over time and