There are a lot of things I like about this game. The writing is generally good, the concept is very original, and it has a lot of innovative and interesting game mechanics. I even like the characters, and the concept of the player character being a soul-eating demon is great.
The backstory and fluff are really interesting... but the combat system makes digging my own eyes out with a spoon look like an entertaining alternative use of my time. It's just really, painfully, torturously boring.
This is an ARPG. The majority of the game is combat. There are a few really glaring things wrong with it and I have no idea how they made it into the game. Did anyone even play this game before they shipped it? It seems like some testers would have said 'hey, these things aren't fun at all, you should get rid of them.'
1) Healing is all or nothing. You're either near a checkpoint where you can restore your entire party to full health, or you're relying on very rare and expensive healing potions that give you back a small fraction of your health. Until mid to late game where you have reliable passive health regen from gear and skills, this means you're going to be stopping in the middle of a dungeon, running all the way back to the checkpoint in town to heal, and then resuming. Seriously, guys? This is a horrible mechanic.
In the early game, the most reliable way to heal a Puppet is to get it killed and then revive it because healing potions are way more expensive than nearly instant full-health resurrections. What?
2) You want to clear every area twice, once in 'reality' and once in the Shadow, the demon world. This is exceptionally tedious. There are trash mobs all over the place, in both dimensions, like any ARPG. The difference here is that you can't clear them rapidly. Damage scales very, very slowly, even for nukers, so you're stuck in lots of drawn-out fights. But if you don't do this, you miss quests, solutions, and content. This means even small areas take a while to clear, and not in a good way.
3) Each character only has seven abilities ever, of which you can use four at a time. There's no real sense of character development. Getting new Puppets is cool in a Pokemon kind of way.. but I feel like I'm playing a MOBA with an hour lapse in between level-ups. I would really prefer less Puppets but more customization and choice per Puppet, with each Puppet you select having a more RPG-style impact on the game. I really wish they would continue to follow the format of the very first Puppet choice, which is a Professor Oak-style pick between a couple interesting souls of dead people for you to eat and use as your first 'character'.
4) Did I mention that the combat is really boring? Because oh gods, it is. Character pathing is awkward at best, so most combat involves using your one to four abilities, waiting for them to come off of cooldown, and then using them again. Periodically you move between groups of enemies or switch between Puppets. In boss fights you sometimes dodge (awkwardly) around telegraphed attacks. That's about it.
5) Character development is really, really, really slow. Gear is strictly level-based, and all your damage scales off of the quality of your gear directly. Adding a small fraction of bonus damage to your autoattack or to an ability is not a rewarding level-up mechanic, but it's all you get.
I've been playing a lot of ARPGs this year, especially D3 and Grim Dawn, so the glaring failure of Shadows: Heretic Kingdoms' combat is very noticable to me. The story is entertaining and I really enjoy the game's writing and premise, but having to sit through 45 minutes of really tedious combat for every 15 minutes of story is not a rewarding experience.
I'm going to continue playing Shadows: Heretic Kingdoms and see if my opinion changes after I see the middle and end game, but the early game is very poorly designed from a game mechanics perspective and could use a total rework. It's a shame, because the story seems interesting. An ARPG was not a good format for this game, however. It would have been much better as a cRPG or even a Fable knock-off, because the ARPG combat seems like an afterthought to the game anyway.