Voidsayer is a monster catching, dark fantasy RPG inspired by, you guessed it, Pokemon and Darkest Dungeon. The premise is that the world has been overrun by all manner of horrors. As one of the last few people standing your job is to head out into the wasteland, capture some of the alien entities and utilize their powers to defeat the rest of their kind. And if you fail, humanity is almost certainly doomed, so you know - no pressure!
And much like most of these types of games, Voidsayer begins in the most classic way imaginable - a strange old man corners you and forces you to take one of three deadly critters off his hands. In this case a dragon, a bad pun, and Cthulhu. Naturally I immediately went with the dragon, because it's a friggin' dragon, though I would've also been fine with Cthulhu. If you actually decide to go for the cabbage cat in this scenario, I'm sorry about the direction your life has taken you and I sincerely hope that things get better for you in the future.
Video version of this recommendation (~13 minutes)
Once you have selected one of the two starter Pokemon, or entities as they're called in this reality, you'll need to prepare yourself to venture out on an expedition. Naturally, since this is the end of the world and your task is super important, the town will provide you with... literally nothing. You'll have to purchase all of your supplies with your own money! I guess some things never really change.
In the demo these items included healing potions, snacks for the road, as well as seals that you can use to capture new entities for your collection. The catch, much like in Darkest Dungeon, is that all of your consumable items get destroyed at the end of an expedition. And since each mission is randomized in a roguelike fashion, you'll never really know what awaits you. As such, buying supplies comes with an interesting degree of risk. Do you spend all your money to ensure a mission goes smoothly, or do you save up so you can buy a much, much more expensive permanent upgrade? I mostly opted to play it safe because even in the first couple of missions a streak of bad luck frequently left me limping over the finish line.

How could I not take the dragon?!
A roguelite adventure
The missions themselves take place on a Slay the Spire inspired map where you get to make your own path by choosing between a variety of randomized options. This is also where the Darkest Dungeon influence creeps back in, because many of your choices are going to be between different flavors of bad. Do you want to take damage? Maybe get corrupted which gives your team debuffs for that mission? Or perhaps just launch yourself into a fight which could be worse than both of those combined?
Thankfully, Voidsayer isn't all cruel. Sometimes the connections between events also come with their own little effects, each denoted by a color. Most are good, but since they could lead you to something dangerous, actually getting good use out of them can be quite tricky. Some items and locations also give you the Scouting buff - thus revealing nearby locations and letting you avoid the really nasty stuff. And most importantly, the more the game slaps you around the more your luck stat will build up - essentially guaranteeing you don't just get crushed under the weight of bad dice rolls.
It's a neat system, and one that I can see giving Voidsayer quite a lot of replay value, but it does feel a bit overwhelming at times. Despite doing three playthroughs of the demo and exploring each available mission multiple times, I still found myself forgetting what certain colors and debuffs actually meant. This didn't affect my enjoyment of the game since the minute details didn't really matter, but I would still appreciate it if the full version comes with much cleaner UI for these things. Stuffing everything into three gigantic pop-ups is not the way to go!

It's very similar to Slay the Spire, but I see no shame in copying a formula that works well
Like Pokemon... but more complex
With all of that in mind, I'm sure it'll come as a massive surprise to hear that Voidsayer's combat is very similar to Pokemon's, just more complicated. So while you can have multiple entities in a party, they can only fight in one-on-one battles. You can swap them around during combat, but unless you do so after one feints you'll be taking a hit for free. That's generally still worth it because Voidsayer also has creature types with strengths and weaknesses - so a fire entity will roast grass types, but will in turn get soaked by water types. Fairly standard stuff, but it's a system that works well so I don't see the need to change it.
Where Voidsayer differs is in its abilities. Even the most basic attack, Voidsayer's variant of the humble tackle, has special effects it can apply to enemies. And the more powerful the ability, the more stuff it's generally capable of doing. Since the demo only covered the early game I can't judge just how impactful all of these buffs and debuffs actually are, but given that the difficulty is relatively high I'd imagine you'll actually want to start paying attention to them in the mid to late game. If that's the case, I'll once again need to repeat the need for having a clearer UI. There's plenty of room on the screen. I shouldn't need to squint at miniscule icons like a 90-year-old grandpa in order to get a sense of what my ability actually does.
Voidsayer also plays around with ability limits a lot more than Pokemon. Each ability only has a small amount of charges, so unless you use a restorative potion each entity will only be good for a couple of battles before you'll need to swap them out. Furthermore, repeating the same abilities over and over again reduces their damage, so you're actually incentivized to mix things up rather than just mash buttons. This is something I really like because it makes you use all sorts of different entities and abilities - things you might've completely skipped over otherwise.
The difficulty also helps in this regard. Between limited ability counts, random events and monster encounters, it's damn near impossible to rely on a single overleveled entity to carry you through every fight like I did in Pokemon back when I was younger. Instead you're going to have to swap entities around, and frequently to make use of the passive regeneration while traveling, which really helps keep things from becoming stale. So as long as the balance in the full version remains tight, I can definitely see Voidsayer being a lot of fun to sink my teeth into.

The combat is simple to get into, but there's a lot of stuff going on
The many flavors of Entities
And speaking of teeth, it's finally time to start talking about the things that have them - the entities. Voidsayer features the usual monster lineup like fire slugs, cool dogs and angry birds, but also some more 'out there' creations like ghouls, surprisingly detailed spiders, and even the most ungodly creature of them all - a mime. And much like Pokemon, the vast majority of the entities have evolutions, though sadly this whole system was not present in the demo so I can't say much more about it.

Even the dragon is horrified!
What I can say is that I generally like the design of the entities. They're very stylish in that Darkest Dungeon sort of way, and their animations - while very simple - are similarly charming. And since I had to go through literal hell with some of these critters, I also found myself quite attached to them and their antics. I just wish I was able to rename them, however, because the default 'species' names are kinda lame. Why is the sentient tree simply called an "Ent"? Why is the teddy bear looking thing just a "Teddy Bear"? Why is my dragon called "Ignisurge"? This might just be me, but compared to the excellent character designs the writing feels like it dropped the ball so hard it's currently tunneling its way through the planet's core.
So how do you get new entities anyway? Fairly simple really. You purchase capture scrolls while at base, and then you use them on non-boss enemies you encounter in the wild. The better and more expensive the scroll, the higher the chance it'll give you. With the most basic one you can use upwards of two scrolls per battle to give yourself a 60% chance to capture an entity once you defeat them. A simple yet elegant system.
The only thing I wish was better here would be the leveling process. Capturing a cool entity and having it start at half of your party's level just means you're going to need to do a bunch of grinding in order to make them actually useful. And honestly? I'm not about that kind of life. I don't know if the full version will have this or not, but I do hope there's going to be some kind of experience share, or better yet an experience potion we could buy in order to kickstart new arrivals. Just anything to avoid the classic Darkest Dungeon problem of having to constantly farm low-level missions in order to get a new batch of recruits up to par.

That is just straight up a skeleton
Building a safe haven
And since I'm already talking about Darkest Dungeon, this is also a good time to mention that Voidsayer let's you slowly build up your city in order to unlock a variety of small bonuses. Stuff like: extra healing when coming back from missions, a chance to gain more loot from chests, a free healing item at the start of each expedition, and so forth. I'm a sucker for games with tiny bits of base-building, so I found this to be a welcome addition. Nothing so complex that it would detract from the actual monster-catching gameplay, but engaging enough that I was always looking forward to getting the next building upgraded.
The same goes for the various equippable items you can find, craft or buy. They either enhance your character and give you more options during the missions, or they give relatively minor buffs to your entities. While I'm sure this will get massively complex later and that someone will min-max the hell out of it, I found it to be a fun little puzzle to solve in between missions as the items don't matter that much, yet still offer enough benefits that you do want to try to give them to the 'correct' entity. And once you're done with that you simply dive into a new mission, get a whole bunch of new stuff to muck around with, and then the process repeats until you either finish the campaign or get distracted by any of the (likely) 50,000 other games in your backlog.

I think you can see why I compare Voidsayer to Darkest Dungeon so much
Closing thoughts
To sum it all up, Voidsayer is a charming and mildly challenging monster catching RPG with just enough roguelite elements sprinkled in to give it that bit of extra kick. So if everything I've shown you looks like it's up your alley, I'd recommend keeping an eye on Voidsayer's upcoming release, as well as giving the free demo a try. You can get a solid 2 hours out of it on your first run, so it should give you a pretty good idea of what you're getting yourself into. Enjoy!