Samsara (SAMSARA-V0.3666-BETA.PK3)

Samsara allows you to play as a formidable complement of classic FPS heroes and either duke it out in deathmatch or slay monsters alone and in co-op. The intent was to provide something like Marvel vs. Capcom for Zandronum. Term eventually discontinued development when he moved on to a new project to drive all the Doom players crazy - Demonsteele - but Kinsie of Reelism fame eventually took up maintenance of the mod so that you can use the same package in both GZDoom and Zandronum just as easily as you can use all of the heroes in any of the idtech1-derived games.

Skulldash (SKULDASH.PK3)

The vast majority of PWADs we see don't really muck with the core format of Doom. Even when we throw true three-dimensional geometry and custom monsters and weapons, you are still working your way toward a finish line of some sort, whether it's a literal line or an exit switch or the death of the Final Boss. Skulldash, a Zandronum megaWAD developed by Joshua O'Sullivan aka "Dragonfly" and released in 2015, has these same conceits, but there is a significant change in what it means to complete a level that shares one aspect of 2014's Doom: The Golden Souls. Specifically, you've got to pick up a certain number of collectibles to make it to each exit. The difference is, you're on a time limit, and when your hourglass runs out, you're dead.

Back to the Fire (BTTF.WAD)

BACK TO THE FIRE
by Simon Dupuis

I've never played the PSX version of the Dooms, and while I've dabbled in Doom 64, I haven't given it good enough of a look to be intimately familiar with it. What I do know is that to some players, both Dooms are the iconic experiences driven by their nostalgia trains, and oppressive ambiance plus colored lighting constitute much of that feel. Back to the Fire, released in 2012 by Simon Dupuis, is a single map for Doom II that uses these elements to I feel evoke that sensation but in a more modern sense. Replacing MAP01, it's meant to be played in the GZDoom engine or Skulltag (now defunct - use Zandronum). Apparently, it's not strictly necessary to play the level in GL ports, but you'll miss out on the colored lighting, and that's a huge part of the level's draw.