Blood is a PC first-person shooter that utilizes Ken Silverman's Build engine, developed by both 3D Realms and Monolith Productions. Though it was conceived and partially developed by 3D Realms, prior to its completion the game and all rights were sold to Monolith as detailed in a press release on January 22, 1997. This was ostensibly meant to allow 3D Realms the ability to focus on Shadow Warrior, which was being developed concurrently. Monolith completed the game as well as an expansion pack entitled Blood Plasma Pak, which were both released in 1997 (a second expansion, Cryptic Passage for Blood, was developed by Sunstorm Interactive).
The version of the Build engine used for Blood included a number of upgrades, most prominent being the ability to display voxel-based objects. This feature was used significantly throughout the game in place of flat sprites, highlighting both weapon and item pickups as well as certain environmental objects such as tombstones, chairs, and barrels. Unlike other contemporary Build engine titles, Duke Nukem 3D and Shadow Warrior, Blood's source code was never publicly released, thus no source ports exist for it, and it must still be played through its original DOS executable.
The gameplay of Blood is very similar to that of other FPS games of its era such as Doom and Duke Nukem 3D. The player is presented with four episodes, which can be played in any order. Each one consists of eight or nine levels (with one secret level per episode) that the player must fight through, with the last level invariably containing that episode's boss. In addition to combat with various types of enemies, most levels require the use of switches and up to six keys in order to advance to the exit. As was the hallmark of its predecessor, Duke Nukem 3D, levels in Blood often place a high emphasis on interactivity, incorporating numerous destructible elements and various objects that can be interacted with for no reason other than increasing the player's immersion.
True to its name, a significant effort was made to amp up the blood and violence over other Build engine games. Zombies can be decapitated and their heads kicked like soccer balls, various enemies can be set on fire to run screaming throughout the levels, and blood flows copiously from enemies at even the simplest of attacks. The game's health system was also relatively novel. Caleb relies for the most part on Life Essence to heal himself, which is dropped by enemies upon death, rather than on preset health pickups used in most first-person shooters at the time. Another innovative aspect of the game was its weapons. Blood boasts alternate firing modes for a large portion of the game's arsenal (a fairly uncommon feature in 1997), ranging from rather straightforward options like firing both barrels of a double-barreled shotgun to more outlandish ones such as lighting and throwing an aerosol can.
Blood puts players in the shoes of Caleb, a protagonist much in the same tongue-in-cheek vein as Duke Nukem and Lo Wang. While the Duke Nukem and Shadow Warrior franchises focused on satirizing action and martial arts movies respectively, Blood traffics in the tropes and mores of the horror genre. The referential humor of the game draws from many sources, from horror classics like The Shining and Friday the 13th, cult films like Army of Darkness, to non-horror classics such as Jaws. Caleb is the game's anti-hero, a sadist and former cultist on a quest for revenge after being killed by Tchernobog, the evil god he once worshiped. In keeping with the game's darker leanings, Caleb is not portrayed as a particularly empathetic character. He will often laugh gleefully in the midst of slaughtering his foes, and will even willfully kills innocents.
As the game begins, Tchernobog has called his Chosen, Caleb, Ophelia, Ishmael, and Gabriel, to a gathering in the Hall of the Epiphany. When they ask what he desires, they are surprised to find he is displeased with them, and they are quickly set upon by Tchernobog's minions. Ishmael is cremated by Cerberus, Gabriel is carried off by Shial who descends from the ceiling, and Ophelia, Caleb's love, is abducted by Cheogh. Finally, Caleb himself is killed personally by Tchernobog, and buried thereafter.
At the start of the game's first level, "Cradle to Grave," Caleb awakens in his own tomb. Upon returning to life by unknown means, Caleb exclaims "I live... again!" Thus he begins his quest, seeking vengeance for his fallen comrades and knowledge of why his own master would betray him.
Caleb searches for his lost love, Ophelia Price, who has been taken by Cheogh.
In order to discover the fate of his fellow Chosen, Gabriel, Caleb delves into the lair of Shial, the Mother of Spiders.
Caleb seeks vengeance on Cerberus, the beast responsible for the death of Ishmael.
Having slain all of his lieutenants, Caleb sets his sights on the evil Tchernobog himself.
Blood shipped originally with twelve weapons, nine of which came with alternate firing modes. The Plasma Pak later added new firing methods to the Incinerator and the Life Leech, which left only the Pitchfork without an alternate mode. While Blood does have a few FPS staples, such as a double barreled shotgun and the Incinerator, a device which is more or less a rocket launcher, a fair number of the game's armaments yield unique and interesting effects.
Thompson's Machine Gun (aka Tommy Gun)
Incinerator (aka Napalm Launcher)
There are three main types of items in Blood: heath & armor pickups, inventory items, and power-ups. The first category increases the player's vitality and damage mitigation, the second consists of items which may be carried and used at a later time, and the last includes items that grant powerful temporary benefits.
Crystal Ball (Multiplayer Only)
Cloak of Invisibility
Blood opponents are generally divided into three categories: low-level, standard, and boss. The first group is composed of smaller foes that pose more of an annoyance than a true threat, and can generally be defeated with little firepower. The second consists of normal sized enemies that can cause more damage and take more of a beating. The last group is comprised of exceedingly rare monsters that are found at the end of each episode.
BatBats only loosely qualify as enemies, as they don't actively seem to be interested in harming the player, and it is only really possible to be injured by one by wandering into its path. Given a wide berth, they can be safely ignored.
RatThe lowest form of land-based enemy, Rats are nonetheless dangerous as they will scurry quickly toward the player where they are much more difficult to target. They are too small to climb even minor ledges, however, so finding higher ground can often leave them harmless.
Bone EelOne of only a couple aquatic enemies in the game, Bone Eels are the seafaring equivalent of Rats. Seeing as it is usually prudent to spend as little time underwater as necessary, it is in many cases wiser to swim past these creatures to dry land rather than waste ammo and risk drowning in order to fighting them.
SpiderThe only low-level creature to come in two varieties, Spiders are notable for the status effects they inflict on the player. The bite of a Red Spider will cause a disorienting camera tilt effect for a few seconds and the Green Spider can cause temporary blindness. Special care should be taken when spiders are in the midst of other enemies, as either of these effects can make a simple firefight extremely difficult.
Choking HandEasily the most dangerous foe in this category, these disembodied hands latch onto the player's neck and quickly drain life until they are removed. This is accomplished by repeatedly pressing the use key, and once done the Choking Hand must still be killed lest it attach itself again.
ZombieZombies are the game's basic opponent. Equipped with a simple axe melee attack and relatively low hit points, they run headlong at the player attempting to hack them to pieces. Due to their lack of any ranged attack, they are not particularly threatening even in large numbers, though fights in close quarters can present a challenge. Zombies in some cases are able to get back up after being knocked down.
Bloated ButcherA larger, slower, and more corpulent version of the standard Zombie, the Butcher comes with significantly more hit points and two projectile attacks, a cleaver toss and the ability to spew corrosive vomit. Neither projectile is extremely quick, so staying at medium range can allow quick players to avoid damage long enough to whittle him down.
Cultist / FanaticPerhaps the most consistently troublesome enemy in the game, both versions of this foe come equipped with a deadly hitscan weapon which can rapidly drain the vitality of even a healthy player. The brown-cloaked Cultists have shotguns, while the gray-garbed Fanatics carry tommy guns. Both wield dynamite, and either can cause significant damage any time they have line-of-sight with the player. They will also occasionally go prone in order to avoid return fire. Cultists and Fanatics drop ammunition for their respective weapons upon death.
GargoyleFlying enemies who often lie in wait as inconspicuous statues, Gargoyles are extremely hardy and have a penchant for attacking the player when otherwise occupied. They can rip at the flesh up close and toss a bone projectile while at range. Staying close can be a valid strategy, as they will usually forgo ranged attacks when near the player. Stone Gargoyles are essentially Cheogh in all but name, and should therefor be treated as such.
Hell HoundWhile they have a melee attack when in close, it is their fiery breath which makes Hell Hounds truly dangerous, as the flames can sap significant vitality before they go out. They are best killed before they get near, though their speed makes this a tricky proposition. Either take them down quickly, or find a means to keep them at bay.
Gill BeastThough indigenous to water, Gill Beasts will follow the player onto dry land given the opportunity. This is somewhat of a blessing, as their lack of any ranged attack makes them fairly easy to dispatch. While submerged, they behave more or less like a larger, tougher version of the Bone Eel.
PhantasmSemi-ethereal beings who are only vulnerable while attacking, Phantasms have both a scythe and a ghostly project at their disposal. Watch for them to turn from partially transparent to opaque, as that is the cue to attack. Its scythe in particular causes tremendous damage, so properly timing one's attacks is crucial.
Cheogh (aka Stone Gargoyle)The Lord of all its brethren, Cheogh is a massive gray Gargoyle with incredible resilience. He fires a pair of blue fireballs from his eyes that travel with great speed toward the player, and his wings allow him to move quickly around the field of battle. He is encountered at the end of the first episode as well as later episodes where he is rechristen the Stone Gargoyle.
Shial (aka Mother Spider)The proverbial "Mother of Spiders," Shial lives deep within the earth surrounded by her eight-legged spawn. Though she is quite large and capable of conjuring her fellow arachnids, there is not much else to distinguish her from other Spiders. In fact, she cannot attack directly, making this unequivocally the easiest boss encounter in the game. Shial awaits at the end of the second episode and also shows up in later levels as a regular monster, though this version is referred to as Mother Spider.
CerberusCerberus is the penultimate boss of Blood, being a larger and tougher two-headed version of the standard Hell Hound. True to his infernal nature, he belches fiery death at all who enter his lair, being able to hurl explosive fireballs from both heads simultaneously. His tenacity will also spur him to attack even after his first head is killed. Cerberus can be found in the third episode as a boss as well as a couple of instances in the fourth episode.
TchernobogEvil god and former master of Caleb, Tchernobog is an exceedingly powerful entity and the leader of the Cultists and other monstrosities the player fights throughout the rest of the game. He is capable of setting the player on fire as well as conjuring explosive blue flames. He is the final enemy to be confronted in the game's fourth and final episode.
Blood saw two commercial expansions, Plasma Pak, created by Monolith, and Cryptic Passage, developed by Sunstorm Interactive. Both add-ons augmented the original game with an entirely new episode (bringing the total to six), with Plasma Pak also having other notable additions such as new enemies and new firing modes for existing weapons. Having the Plasma Pak installed also allows these new firing modes to be used in Blood's original episodes.