Nitemare 3D

Nitemare 3D was a haunted-house-themed First Person Shooter for DOS and Windows 3.1 based on Wolfenstein 3D and released in 1994. It was nominally a follow-up to the Hugos House of Horrors series of adventure games, but instead of solving tricky Adventure Game puzzles, you just shoot stuff. Well, and collect keys and cards needed to advance to the next level. And find hidden passages. And solve the occasional Block Puzzle. Expanded greatly on the concept, with the aforementioned features as well as an on-screen minimap showing the nearby areas you've visited as well as any enemies in the vicinity.

Still has a cult following, due in part to being continually updated for compatability with the latest version of Windows.

This game provides examples of:

 * Blackout Basement: One sequence in Level 1-7 has the storm blow out the fuse.
 * Block Puzzle: Possibly the first FPS to use these.
 * Bloodless Carnage: In contrast to its famous predecessor, enemies don't even fall down dead (except for bats); they either simply vanish when killed or morph into tombstones or... flower pots.
 * Bookcase Passage: Tons of secret sliding panels, which, aside from the actual bookcases, are impossible to tell from the regular walls without your handy secret-panel-detecting eyeballs.
 * Call Back: To the Hugo series -- the first safe is unlocked with the combination.
 * The Computer Is a Cheating Bastard: Enemies that shoot can shoot around corners you can't even see around. Possibly just a side effect of poor programming, though.
 * Dem Bones: Skeletons that throw flaming bones, or something.
 * They toss torches, though if you're close enough to make that out when they do that, you're about to take a lot of damage.
 * Enemy Detecting Radar: Collecting the floating crystal balls fuels an overlay for your Level Map Display that shows enemies in red.
 * Family Friendly Firearms: The game starts you off with a plasma gun despite the current-day setting. Subverted in level three, however, when you find the pistol.
 * ~Frankenstein's Monster~
 * Healing Potion
 * Also the Pentagram of Good Heath, which restores you to full health, always.
 * Hundred Percent Completion: Hitting TAB brings up a chart of how many enemies there are left to kill and how many secret panels have yet to be found.
 * Kinetic Weapons Are Just Better: The plasma guns and magic wand all fire relatively slow-moving projectiles. The pistol hits its target instantly (albeit with more of a delay between shots and the inability to blow the exploding walls), making it a godsend for enemies whose ranged attacks do likewise.
 * Level Map Display: The aforementioned map in your HUD, which drains a meter powered by giant floating collectable eyeballs.
 * Locked Door: Every wooden door is initially locked, and you will need one of up to four color-coded keys (depending on the level) to open them. The final door of each level also requires an ID card to unlock, and if there are any wooden doors in the level, you can bet that card will be behind one of them.
 * Made of Explodium: Some of the specially-marked walls.
 * Mummy
 * The Power of Rock: In Level 1-9, switching on a radio makes enemies dance out of your way. Good thing, too, because your weapon jams just as you enter that room.
 * Secret Level: Level 1-5.
 * Shareware: Just like Wolfenstein, the first ten-level "episode" was free, and registering got you the other two.
 * Sound Coded for Your Convenience
 * Standard FPS Guns: Averted. There is a pistol, but it's the last of the three weapons you find. The others are a Plasma Gun (which kinda fits as a first weapon but only as it's handgun-shaped) and a Magic Wand.
 * Sorting Algorithm of Weapon Effectiveness: Also averted. Each of the three weapons are more effective against certain enemies and less effective against others. According to the manual, the Wand is better against Witches and Sorceresses, while the Pistol is loaded with silver bullets and thus better against Vampires.)
 * Unwinnable By Design: Most of the times, you'll want to kill off any enemy around as soon as possible, but in a select few situations you'll need to coax enemies into blocking off certain passageways. Killing those enemies too soon makes the level unwinnable.
 * Wall Master: Two versions, one for the stone-walled dungeons and one for the hedge mazes.
 * Wicked Witch: Now in three different flavors!