It's a Metroid themed Doom map. Metroidvania-style.
Version 2.2 fixes the Walker's death animation for real, improves ACS music changing, prevents Unholy Massacre from showing in LZDoom, removes some unnecessary...
Version 2.1 adds a TITLEMAP, makes the default Power Beam faster, adds new firing frames to the Missile Launcher, (hopefully) fixes the Walker's death...