I just finished a Doom 2 mod called Winter's Fury. In it, the Doomguy is given a name(!) and sent to Siberia to deal with an issue there. Obviously, the issue is all the congressmen, car salesmen, and insurance providers are acting up again. And, being Siberia, it's figgin' cold.
All that aside, the creators of this mod did a pretty good job pushing the envelope of what the Doom engine is capable of. The atmosphere is great, it feels cold in the maps. There were moments that surprised even me, and I'm a 20 year veteran of Doom playing, and have seen it all.
Most of the maps were well made, not too short and not too long, with large areas made outside of bounds so that it wasn't feeling like an artificial enclosed world for each map, like most Doom maps. Looking off into the horizon at places, you could see islands in water, areas of the mod you'd been to or were going to, and tracts of land never used for anything but creating a sense of being part of the world.
Only one map drug on too long, which was a sprawling, confusing affair that twisted back on itself, and had no clear sense of direction. Then you ended up repeating that same map in the very next part, at least partially. I think I spent more time there than the rest of the mod.
Only one (very bad) bug was toward the end, a boss which could not be hit from the ground. I had to use a cheat to climb on top of some pillars to fight him.
Ammo got tight toward the end, though the boss fights generally had liberal amounts scattered around. Most of the enemies were of the congress-sort, no undead.
You will need the GZDoom source port for this one, as it has some tricks not usable in the vanilla Doom engine, like true 3D floors (floor on top of floor) and swimmable water in one spot. I don't know if it'll work in ZDoom, Doomsday, or any other port.
All in all, not a bad mod if you like the classic Doom-style gameplay. On top of that, the weapons have been tweaked, with new graphics and some sounds, and minor tweaking to their capabilities. Only the BFG and chainsaw are not represented.
As an aside, it's amazing to me that a game 20 years old is not only still developed and worked on, but has so much new stuff coming in that there is even an annual awards event over at Doomworld.com. This is how you do it, EA, Ubisoft, and Activision. The game has always been easily available for sale, no DRM viruses, modding was supported from the start (and is easier than ever with all the source ports and community-built tools), and the source code was released once the engine got outdated, so the game has been kept up to date with new OS releases by the community. For free.