Not counting the Nocturnal Missions (which I will eventually also play), I beat this one in a couple hours. Early on I was a little less than impressed, perhaps going from Doom and Doomclones to a predecessor was destined to initially disappoint, at least in technicality, but by the end i'd come away liking this one. The levels feel cramped and the enemies hit a bit too hard, but honestly those felt like positives the more I played. As much as playing this sort of game can be fun as a mindless powering through several hundred enemies, there's something just as satisfying about being more careful, and beating a level with minimal damage taken after sneaking your way around. It just fit the atmosphere of the game. Graphically it's obviously very primitive compared to a lot of the later retro FPS styles that i'd prefer aesthetically, but it was fine enough and I can't say I look to these kinds of games for stunning visual experiences. This did exactly what I needed it to do, and that was let me shoot my way through roughly thirty entertaining maps of enemies with boss fights that are mostly underwhelming. That's the Retro FPS way.