Heretic is ok but feels like it misses most of what makes Doom good. It is cool to see some new weapons and enemies but there isn't much beyond that.

The level design here is more straightforward, with almost every mission just being a collect the keys in order as you fight through rooms of enemies sort of affair. There are a couple with some interesting teleportation or exploration challenges, but for the most part these feel like straightforward, fantasy caves and temples. I do like that the levels feel much different than Doom though.
I like the art in Heretic quite a bit. It presents a bright, Saturday morning cartoon version of fantasy with saturated colors and lighting that gives it quite a contrast to the dark hellscapes of Doom. Things like the final boss, D'Sparil being the guy that you have seen over and over in the stained glass windows throughout your ordeal are cute and fun.

The weapons start out promising but the team seems to run out of ideas fairly quickly and most of them fail to really make a case for their inclusion here. Individual weapons don't feel suited to defeating particular enemies or particular challenges and where Doom makes your ammo resource an interesting source of power increase (from the pistol to the chain gun) or decision-making (between the energy rifle and the BFG), ammo here just ammo. Each weapon has a different type and you sort of cycle through your armaments as you run low on a particular type. It isn't really very satisfying or fun.
The Spectral Crossbow is by far the standout to me, with its somewhat interesting shot pattern it functions like a hybrid of a shotgun and a sniper rifle.
Enemy design doesn't do the weapon designs any favors. New enemies are introduced throughout most of this three episode campaign and they have different attacks, but your approach to them never really changes. Fighting a Maulotaur is basically no different than fighting a golem, it just goes on for longer.

Heretic plays well enough, but definitely feels like a by the book proof of concept done by a team that didn't really have a clear idea of what makes Doom's systems or level design work. I do love the swing at making this weird, fantasy fast-follow to Doom even if it ends up being a fairly mundane experience to play through.

As the first entry in a series, Heretic is the coolest "Doom clone" out there, featuring amazing weapons, wicked monster designs and great levels throughout 3 episodes (+2 with the expansion) with a very simple story where you need to kill one of the Serpent Riders.

I am not gonna lie, Heretic is as simple as it gets, even with the added features such as an inventory for items. It has magical weapons, staffs and artifacts but they are pretty much identical to the weapons in Doom, so anyone can find their favorite in no time. What makes this game unique is the levels themselves, offering great visuals with challenging designs. The enemies are fun and unique, and the whole game does not need to be called a "Doom clone" as the game has a lot to offer on it's own.

If you never played Heretic before, I would recommend it, especially if you are interested in Hexen.

Gameplay: Good
Story: OK
Controls: OK
Graphics: Good for its time
Length: Good

(Played the Steam version of the three original episodes on ZDoom, Bringest Them Onest difficulty)

Another game I get to replay after almost 30 years... It's Fine. As other reviews have already said, it deftly negotiates the potential pitfalls of using the engine of a game as iconic as Doom, adding and modifying enough of the experience so it doesn't feel too derivative. The inventory system is pretty neat, though aside from being able to stash potions to heal on demand and using the tome of power to power up your weapons, the other items are either situational or gimmicky, and the levels aren't really designed around them so they feel like an afterthought. The aesthetic is where it really shines, with the gothic architecture and more piano-heavy tracks setting it further apart from Doom.

My gameplay experience didn't measure up to Doom's though, and it was down to some very marginal differences:

- The exploration aspect is a tricky part of FPSs in this mold, where linearity is boring but overly-obtuse key and switch hunting gets in the way of the action, and you end up endlessly combing through areas you've already cleared to try to find the way to advance. Heretic gets that balance off a bit too often for comfort, with a particularly egregious example in the Cathedral level where a switch required to progress is in a hidden room behind an unmarked wall.
- The lack of 'glass cannon' enemies. Unlike Doom's 'human' enemies (and the Revenant to a smaller extent), there are no enemies with hitscan attacks here, and no enemies that are very powerful but not durable. This reduces a bit of the split-second strategizing when you look at an enemy formation and decide who you absolutely need to take out first.
- The general difficulty curve is solid, but thanks to the sprawling level design, too many of Heretic's challenges can be overcome by simply kiting enemies and then circlestrafing; even the episode bosses were quite easy outside of their massive durability. There were a few good challenges such as Episode 1's final level where the presence of lava neuters your circlestrafing strategy, and I wish more levels used the level design and the enemy formations to create difficulty in a more organic way.

It didn't quite hit the same heights as the game that inspired it but it is a solid game! The fact that they were able to adapt fantasy tropes to the budding FPS genre does earn it a lot of goodwill, and based on that alone I would say this game is worth at least a cursory playthrough for anyone.

I'm pretty partial to this style of game anyway, so this being yet another of the very early Doom-style of shooter with a memorable, enjoyable aesthetic to it and a decently breezy playthrough meant it was hardly going to settle lower than "this is pretty great" in my estimation. It's decently short too, only three episodes (with a couple more with the version I have that were part of a DLC), and each one has decently fun locations, interesting enemies and cool weapons. Really not much else to be said than that. Simple, very fun, and that's what i'm looking for with this stuff. Definitely playing the two expansion episodes next.

Doom with wizards. I can say that I enjoyed this experience more than Hexen, but I still like both takes for their own reasons. This played quite straight-ahead; it really did just feel like Doom with medieval flare. Generally good level design and nice enemy variety / placement throughout. Later levels started to slog a little bit simply due to lack of variety, but I'm sure that's also because I was blasting through it super quickly. If you want more Doom with a different coat of paint on it, this is a solid option.

One of the more "basic" Doom Clones—to the point that the first weapon of the game shares the exact same recoil pattern as the Doom pistol. It is, essentially, Doom's arsenal re-skinned, and many of its enemies mirror those in Doom itself.

Which, well, is fun as long as the levels are well designed. And, for the most part, they are.

The less said about the last two episodes the better, however—4 and 5 were so much trouble they made me question whether I was just burnt out on FPS games.

Slightly worse Doom with held items that feel like you're cheating. Flying? Turning enemies into chickens? Warp to the start of the level? On demand healing and invincibility?

Your BFG equivalent kind of sucks and your normal melee is bad with no berserk equivalent. If you need to use the tome for your staff, you're in trouble... Your starting weapon actually being usable for almost the entire time, not sharing ammo with another great weapon and being good? Though I wish you could see all your weapon ammo at anytime, like in Doom. The music is just as great, and the setting really works for me. The boss set pieces were nice, with some unique monsters I was not expecting. The regular enemies could have made a bit more effort to let you distinguish between the different kinds of gargoyles and golems at a glance. 

I'm really excited to see what WADs will do with this foundation.