Wow, quite enjoyed myself with this one! I wasn't all that impressed at first glance as the survivor genre is overpacked with competition, but I was surprised at how this ended up addicting me with its pretty fun gameplay, so kudos in that respect!
The vibes reminded me a lot of 20 Minutes Till Dawn, especially when it comes to the build variety with different focuses on summons, traps, elements, damage, projectiles, reload, and so on: wouldn't be surprised if it was a direct inspiration or straight-up lifting from its playbook, haha! I thought at first that the summon build would be the only fun build, but color me surprised when I liked laying down traps or having light-based radial slowdown/fire or having chain explosions and so on. No matter what the cards dealt it felt like you could get something cool going in lots of different ways!
For the most part, the game was pretty well put-together. As said, I quite like the build variety and the power progression as the game goes along, especially when combined with the enemy escalation with all sorts of different types of enemies that go beyond just simple statistical increases, but actual different patterns that make you change up your strategies. Game also offered a lot of interesting weapons and heroes, and I liked that you can try them out before actually having to buy them (though I was disappointed that there was no way to try out hero super moves).
That being said, while the game is fun, I'm not quite sure about the long-term appeal. The fact that it's just a single map (or rather a single screen) with no special events or quests or modifiers that can really shake up the experience from run to run, can make it feel a bit repetitive and pointless. Furthermore, the game doesn't really have a unique selling point to it: as much as I have fun with it, it is, as I mentioned, just like 20 Minutes Till Dawn, so there's nothing this really gives me that that game doesn't already, so why would I buy this? Not sure if the game is going to develop some sort of story, or multiple levels, or other interesting aspects and content to keep people playing. It doesn't necessarily need to, but without some sort of larger purpose or sense of greater progression beyond just goofing around with different guns and maybe cranking the difficulty, I feel like I wouldn't be compelled to stick with it for long, let alone spend money on it.
In addition to that, there were a few confusing aspects here and there:
*For example, I found it frustrating that you can get cards like +50% poison damage when you don't even have a poison weapon: because you can still get these despite that, players (like me) can be fooled into thinking the card will give you poison damage, only to find that it doesn't.
*I found it a bit odd that killing enemies will sometimes have that explode in a satisfying manner, whereas other times they will just poof away in an awkward manner: thought it was overkill damage at first, but that didn't seem to be the case, so I don't know why there is an inconsistency.
*It was strange that the game doesn't offer a way to manually reload as a strategic decision to make. I also thought the reload bar was a bit odd: I expected it to stretch all across the player, but it ends like half-way.
*Would've liked if there were some HUD elements right next to the player, such as an ammo and health count: it's difficult to keep track of those considering they are crammed in the corner of the screen which is hard to peek at during combat.
*Would also love if the number of damage you took as a player would pop up as it was really confusing to determine how badly I got hurt: maybe it'd be nice if you just normalize damage with hearts instead of numbers? So weird to take '18' damage as a normal thing instead of a basic round number like 10 or 5 (i know, i know, it's because of all the percentage defense stuff you can get).
*Finally, it was really awkward that the visual effect for the knockback that comes with levelling up happens immediately when you level up, but disappears before you're done with the level up screen and then the knockback happens afterwards, making them feel disjointed: feel like you should freeze/delay the visual effect until you're done with the level up screen so that both visual effect and actual knockback happen in sync.
I'd say you have a really solid and fun core gameplay here that I'd love to see iterated upon: best of luck for the eventual full release!