This is a far too slow survivor game, in both the actual gameplay and progression.
You move far too slowly, your attacks are kinda shit, you level up slowly, enemies spawn slowly, and you gain gold slowly.
I don't recall a single standard enemy dropping gold, and bosses don't drop xp. Bosses drop a chest, which (based on the first character only) give something like 15-25 gold, and if you get 3 chests you get the gallery scene for the current character (which is the only way to get the gallery). Unlike every other survivor game I've played (not too many admittedly, but still) the boss chest don't give an item / upgrade.
Permanent upgrades are like many survivor style games, bought between runs. Characters are also bought that way. The issue is the gold gain rate. The first level upgrades are 100-150 IIRC, meaning something like 7-8 chests to get 1 upgrade, which isn't really worth it (or really needed for the most part). Characters cost 600+, it took like a 25 minute run to get 600 gold...
With the very basic knowledge of how to walk around enemies to kite them into a ball you're pretty much invincible, so it's incredibly easy to go a long time, but very boring to do so since the enemies are all basically the same, just more or less HP (including bosses) with about 6 total enemy sprites.
There are 2 extra weapons to get by level ups, unlike other survivor games with 10ish. One weapon is basically completely useless, since the "holy explosion" or whatever it's called hits a random screen location, with a tiny AoE and mostly lands near the edge of the screen when you're almost always kiting a bunched mob at the center of the screen. The curse weapon is similar until upgrades, when it becomes useful by having it target a random enemy instead of a random location.
The art is at least decent, so if you want to see it just use a cheat of some kind to get gold or gallery unlock.