Modders and level creators continue to produce goods for the original Doom. Some even allow you to romance the demons. But nowadays they're often designed for modernised versions: source ports like ZDoom or GZDoom. These are cool, but it's neat to find a new Megawad created for the original DOS game, built under the ye olde engine restrictions (no free look, no slopes).
That's what Rekkr is, but it's not the only cool thing about it. It's a Viking-themed Megawad complete with 25 new levels, boasting its own textures, music and sound. It'll work in ZDoom and other source ports, but you'll get just as much out of it if you load it into the original game (that might be a hassle for modern PC users, though, unless you want to use DOSBox).
Check out the trailer for Rekkr below. If you're after some more cool wads, there's plenty over here, or perhaps you'd like to try some recent maps from John Romero? Thanks to Rock Paper Shotgun for the heads up.