Yes, this game runs on GZDoom. No, it's not a mod. Yes, it's worth every penny. Play through it as blindly as you can, a lot of the wonder comes with the sense of discovery and not knowing next. The gameplay is solid, lots of cool ideas and ways to use the weapons you find, and really satisfying and tough encounters. The environments are creative, interesting, and downright beautiful at times. The secrets are well hidden and rewarding, and genuinely require some sleuthing to find, which makes them all the more fun to hunt down. The music is really nice as well, it certainly adds to the atmosphere. Some Alexander Brandon tracks in there as well, if you like him. Lore is there if you like it, pretty extensive wiki, along with a compelling story that kept me wondering what was going to happen next. All in all, really compelling game, easy 6-8 hour experience, lots of varied environments, enemies, weapons, and overall just a breath of fresh air compared to other retro shooters. Absolute recommendation :)
