Introduction
Developed by Raven Software, Heretic is the game that came after Doom and before Hexen. It only has a few of the engine improvements that would be seen later in Hexen: an inventory system, ambient sounds and "pushing" sectors, the latter being mostly used to simulate water currents and sometimes wind. It also affects some projectiles, which is funny looking if the push is particularly strong and meant to simulate water current that shouldn't affect projectiles flying in the air.
Other than that, it's medieval Doom. You look for switches and keys to ultimately reach the exit teleport/switch. It's structured in episodes of 8 levels + 1 secret level, exactly like Doom 1 was. Nevertheless, it has significant gameplay improvements over Doom:
Much better mapping. There are no levels that will make you groan. There's still some pretty dumb or forgettable stuff, sure, but nothing outright bad. Consequences of better mapping are less "fuck you" traps, less and better overall use of damage floors and less timed door/elevator fuckery. Maps are also usually generous with redundant weaponry, making them more friendly toward speed runs and pistol starts.
No aggravating enemies. There is no pain elemental, arch-vile or revenant. Non-boss monsters all have reasonable amounts of HP so they can be killed fairly quickly. Additionally, there is no monster with a hitscan attack. If you get hit, that's because you didn't dodge, and not because the RNG decided that chaingunner across the map has no trouble hitting you even if you're running at 100 mph.
The weapons, unfortunately, are uninspired. They're nearly straight ripoffs from Doom, with the exception of the BFG which has no equivalent in Heretic. Instead, we get a fairly weak and unwieldy weapon that I would only rank above the wand (pistol) and below every other pickup weapon except maybe the gauntlets of the necromancer (chainsaw). They do, however, have fairly unique alternate, "powered" attacks that are temporarily activated by using an artifact.
WEAPONS
ITEMSStaff Worthless melee physical weapon. Powered up it glows with energy and does more damage, but is still worthless. There's no berserk in Heretic either, so it's always useless.
Elven Wand Weak magical hitscan weapon with a medium rate of fire. Pretty inaccurate too, so you have to tap if you want to use it at long range. Powered up it shoots a spread of hitscan (like a shotgun) and 2 slow moving fireballs. Always uses 1 ammo. Refills: wand crystals (10) and crystal geodes (50). Ammo capacity of 100/200.
Gauntlets of the Necromancer Replacement for the staff. Fast damaging magical melee weapon that "hooks" you to the target monster, just like Doom's chainsaw. Powered up it does more damage and leeches health.
Ethereal Crossbow Shoots a powerful magical arrow and 2 weaker, smaller physical arrows at a slow rate. Powered up it shoots 2 extra magical arrows and increases the rate of fire, yet still only uses 1 ammo per shot. Each bolt is individually autoaimed, so they may go after different monsters. Refills: ethereal arrows (5) and quivers of ethereal arrows (20). Ammo capacity of 50/100.
Dragon Claw Weak but accurate magical hitscan weapon with a fast rate of fire. Powered up it shoots orbs that explode into a ring of magical spiked balls at a slow rate of fire. Uses 5 ammo per shot in power mode. Refills: claw orbs (10) and energy orbs (25). Ammo capacity of 200/400.
Hellstaff Fires a stream of fairly weak magical red projectiles. Powered up it slowly shoots single powerful red projectiles that cost 5 ammo and home on enemies. When one hits something, it makes damaging red rain fall on the area for a duration. Refills: lesser runes (20) and greater runes (100). Ammo capacity of 200/400.
Phoenix Rod Fires a single powerful fireball that explodes on contact. The fireball is physical, but the splash damage is magical and it can also hurt the player who fired it. Powered up it becomes a flamethrower that deals extreme magical damage. Refills: flame orbs (1) and inferno orbs (10). Ammo capacity of 20/40.
Firemace Fires a stream of bouncing metal balls that deal mediocre damage. Powered up it slowly shoots big bouncing metal balls that somewhat home on nearby enemies and instantly kill them on impact, at 5 ammo per shot. Physical and crappy range and velocity in both modes. Refills: small piles of mace spheres (20), big piles of mace spheres (100). Ammo capacity of 150/300.
ARTIFACTSCrystal Vial Heals 10 health when picked up, up to a maximum of 100.
Silver Shield Sets armor to 100. Absorbs 50% of damage taken.
Enchanted Shield Sets armor to 200. Absorbs 75% of damage taken.
Bag of Holding Doubles max ammo capacity (only once) and gives a little of each ammo type, excluding mace spheres. (Why? The firemace sucks.) Counts as an item in the tally.
Map Scroll Completely fills the automap with unexplored area appearing in gray. Counts as an item in the tally.
MONSTERSThere's a max of 16 artifacts of the same type you can carry. Only 1 of each type of artifacts will be brought over into the next map, excluding wings of wrath which can only be used in the maps they're found. All artifacts count in the item tally.
Quartz Flask Restores 25 health when used, up to a maximum of 100.
Mystic Urn Sets health to 100.
Tome of Power Temporarily activates all weapons' power mode when used. Also restores normal form if chickened.
Timebombs of the Ancients Explodes a few seconds after being dropped, doing splash magical damage. Can hurt the player who used it.
Morph Ovum Fires egg shaped projectiles in a spread that transform monsters into chickens on contact for a duration. Chickens can still attack, but do almost no damage and are extremely easy to kill. Works on ghosts.
Wings of Wrath Allows the user to fly for a duration.
Ring of Invulnerability Temporary invulnerability and golden vision when used. Very rare.
Shadowsphere Temporary partial invisibility. Monsters have a chance of not seeing the user and will tend to misfire their projectiles when targeting him. Also turns the user into a ghost, which is almost meaningless in singleplayer since every single monster melee and projectile attack are magical, with two notable exceptions: green and red axes thrown by undead warriors. Against these guys, a shadowsphere is almost as good as a ring of invulnerability. Their melee attack will still connect, however. It also prevents an iron lich's whirlwind from homing.
Torch Grants full brightness when used for a duration.
Chaos Device Instantly teleports the user back to the start of the map.
Ghost monsters are immune to physical weapon.
Gargoyle/Fire Gargoyle Health: 40/80, Damage: 5-12 (melee), 1-8 (fireball). Just like a lost soul, except it doesn't deal damage when it charges. It has to land a claw swipe. This makes it much less annoying than a lost soul. The fireball throwing version has more health.
Golem/Nitrogolem Health: 80/100, Damage: 2-16 (melee), 4-32 (flaming skull). The most common enemy in the game. It runs around and tries to smack you with its fists. The flaming skull throwing variant has a little more health. It occasionally drops a wand crystal worth half the normal amount. One of the two enemy types that can appear as ghosts. The flaming skulls are slightly homing.
Undead Warrior Health: 200, Damage: 3-24 (melee), 2-16 (green axe), 7-56 (red axe). Tall monster that throws green shit at you, just like a Hell Knight in Doom. Sometimes it throws a red axe that does much more damage. It occasionally drops ethereal arrows worth the normal amount. The other enemy type that can appear as a ghost. Undead warrior ghosts never throw green axes, only red ones, making them particularly dangerous.
Disciple of D'Sparil Health: 180, Damage: 4-32 (melee), 3-24 (per missile). Floats around moaning unintelligibly and throws 3 missiles at a time in a spreading pattern. When it charges up its attack, it flickers in and out of ghost mode. Occasionally drops claw orbs worth the normal amount and rarely a tome of power.
Weredragon Health: 220, Damage: 3-24 (melee), 4-32 (fireball). A pretty redundant monster that spits fireballs at you. Occasionally drops ethereal arrows worth twice the normal amount. First appears in episode 2.
Sabreclaw Health: 150, Damage: 3-10 (melee). The pinky demon of Heretic. It's unfazed by damage when it's attacking so fighting it up close is discouraged (though there's a trick that I'll show in the videos). Occasionally drops lesser runes worth the normal amount. First appears in episode 2.
Ophidian Health: 280, Damage: 1-8 (per missile, first 3 missiles), 3-24 (fourth missile). Fires a stream of 4 missiles. Occasionally drops flame orbs worth 5 times the normal amount. First appears in episode 3.
Iron Lich Health: 700, Damage: 6-48 (melee), 1-8 (ice ball), 3-24 (ice shards), 5-40 (fire pillar), 15 per second (whirlwind). Souped up cacodemon, casts 3 different spells (the ice ball breaks into ice shards when it hits something). The most annoying spell is the whirlwind, it aggressively homes on its target, throws it in the air (can be used to take shortcuts) and generally fucks up aiming. Occasionally drops claw orbs worth the normal amount and rarely a morph ovum. It is immune to the effect of the morph ovum and the powered up firemace. First appears as the boss of episode 1.
Maulotaur Health: 3000, Damage: 4-32 (melee), 6-48 (bull rush), 3-24 (per fire missile), 16-128 (ground line fire). A cyberdemon, basically. Tough as hell to kill. Occasionally drops flame orbs worth 10 times the normal amount and rarely a mystic urn. It is immune to the effect of the morph ovum, the powered up firemace, timebombs of the ancients and the splash damage of the phoenix rod's fireballs. It also takes severely reduced damage from the powered up hellstaff. First appears as the boss of episode 2.
The presentation of the information in this post was shamelessly stolen from CyRaptor's Doom II thread.To follow the standard I set in my Hexen VLP, I'll be playing on the hardest difficulty mode and finding all the secrets to show the levels in their entirety. 100% kills and items are also a reasonable expectation, though not a guarantee.
Heretic's "black plague possesses thee" works differently than Doom's "NIGHTMARE!". Mainly, there is no monster respawning, so it's the rough equivalent of playing Doom on ultra-violence with -fast. However, Heretic's fast monsters are a lot nastier than Doom's. All monsters move and attack 3 times faster. Their projectiles travel 3 times faster as well. There is also a 50% increase (rounded down) from ammo pickups. Doom gives 100% more ammo on nightmare.
Videos
HereticEpisode 1: City of the Damned
Episode 2: Hell's Maw
Episode 3: The Dome of D'Sparil
Heretic: Shadow of the Serpent Riders
Episode 4: The Ossuary
Episode 5: The Stagnant Demesne