Sometimes when I enter a room I get the message "Your enemies grow stronger...". How does the game decide when to do that? I haven't found any pattern to it, and it's putting a damper on my enjoyment of the game, because it seems to happen more often the more powerful I am. This means that finding an epic weapon isn't really that great, because it seems like the game immediately adjusts the difficulty so that I'm no more powerful than before.
Tallowmere dev here!
Currently in Tallowmere Alpha 175, when you max your souls out (as in, when your souls reset to zero and your max soul limit increases), enemies will grow stronger two rooms later.
The idea is that you max your souls, turn in your floating soul group to become more powerful for a room or two, and then see how much harder the enemies get. Sometimes you'll get lucky and they stay pretty weak, or sometimes they become a bit more bulkier.
Enemies level up randomly based on your stats. They might gain a lot of health or only a little health; likewise with their attack power.
Looking at my enemy-levelling-up code, an enemy will grow to have enough health to die in 3-7 hits of one of your high base damage weapons and taking into account any +Base Damage stats you have on any gear, but not taking into account any extra damage stats that affect only certain weapon types. 7 hits (potentially) to kill an enemy with an awesome weapon you gained only two rooms ago doesn't feel very awesome, at least near the start of the game anyway. And, if you switch to one of your weaker weapons (say because it's better for the situation), enemies will probably have so much more health that it takes many many hits to die.
And then for increasing enemy damage, your health and resistances are taken into account. But switch to a weapon that makes you lose a lot of resistances, and you'll get hit harder.
With the enemies levelling up two rooms after you do, there's also the case of you not feeling very overpowered for very long in the first few rooms, since the rooms are short. But once your rooms get into the 20s and 30s, rooms feel long and exhausting, and being able to turn your soul group in and then clear a room or two with a bit more ease can feel nice since the rooms are bigger at that point.
This is very much a work-in-progress still. I will probably change it so enemies don't level up too harshly too quickly, so you can enjoy your overpowered loot a bit longer. (I mean, sometimes you get lucky and enemies will stay weakish, like with the 3-hit health amount, but sometimes they can beef up a bit too much perhaps... 7 hits is a lot.) I'll probably tweak it so they only gain so much health or attack power per level-up, maybe down to 5 hits max? And I know the resistances balance needs work.
I could also look at having enemies level up their health based off a random weapon you have, rather than your most powerful one, just to throw in more randomness to the mix.
I am also considering preventing really rare items from appearing in the first few rooms, since the rooms are so short and levelling-up doesn't take much effort, this way overpowered gear won't feel too outdated too quickly.
If the current system really doesn't do it for you, you can speak to the Punisher in town and activate the "Item rarities forced to Basic" punishment, meaning every item will be of 1-star quality.
I also plan on adding elite/champion enemies that really hit hard, and in turn maybe just have the other enemies perhaps be slightly weaker to give the spotlight to the elite enemies. I'm also looking at adding different game modes or individual dungeons that might have their own difficulty levels. Anything's possible really, just a matter of time and effort, playtesting, gathering feedback, and iterating. I want you to feel overpowered, but not necessarily for too long; striking the right balance is tricky!