Doom co-creator John Romero is set to release a new megawad this February, in the form of a fifth episode of the original game. Dubbed Sigil, it features nine levels and even has a fancy physical limited edition, though if you're keen on just playing the levels you can do so for free providing you own a copy of Doom.
But waiting until February is hard. Thankfully Romero has spent the last week streaming two levels from the megawad, culminating in around four hours of footage. That's a lot of hours for two levels, but Romero demonstrates small iterative changes made to the levels over the course of the week, and also talks through some of the design decisions. He also dies: these levels aren't going to be a walk in the park.
Here's the first video. I won't embed them all – if you want to watch the rest in the series, head over to Romero's Twitch channel.