Doom is now playable on Twitter - sort of. Thanks to Tweet2Doom bot, you can send replies to the account with a list of actions - move, turn, shoot, etc. - and get a video clip of Doom showing the results sent back to you.
It's sort of Doom but turn-based. Your best is to send a small number of actions, get a short video back, and then adjust accordingly. That's not stopped some people from doing the opposite though and just speeding through levels. Here's E1M1 completed in 11 seconds, the current record:
You can see from the source tweet that the instructions you need to send to the Twitter bot look complicated - eg. "4-f,13-usf,3-usl<" and so on. This tweet contains the instructions. The numbers define how many frames an action should be performed for, while the letters denote actions. I think my quoted example says: shoot for four frames, then run forward while shooting for 13 frames, then run forward and strafe left for 3 frames.
Players have only managed to complete the first couple of levels so far, and I'd guess it's going to be mighty hard to complete the entire game this way. Which probably means it'll be done by the end of November.
Personally, I'm just enjoying watching other people try, ten seconds at a time. The bot tweets out random collections of clips, too:
Doom runs on everything from a Game & Watch to inside a pregnancy kit. There's a Tumblr dedicated to collecting every newly supported machine. Unlike most, Tweet2Doom is one you can take part in, though. Have at it.