A list of most things I noticed while playing in no particular order.

• quick sell isn't quick
  
• what condition must be meet for the "are you sure" popup

Solutions
rename quick sell to selling
new button that sells all items which aren't locked, either next to the current button or inside menu

option to disable "are you sure" popup ?

• running in animation unnecessary
  
• spawn enemy right on map load not after running in animation is over
  
• timer between rounds is too long, lower (3 seconds) or remove completely which would require the item rewards to be displayed somewhere else.

continue progress while any menu is open.

• player level doesn't remotely match enemy lvl
  
• enemies just get more

Just having more enemies gives no enjoyment as it just slows down your progression. Either stop it entirely or at least give an upgrade that can reduce the amount

make window resizable by dragging on edge of window
or pulling window to edge of screen to take up all space

only drop stolen wood if the daily is active



dmg, attack speed,
crit chance, crit damage if it's separate

this is required to calculate the dps to see if an equipment is an actual improvement

separate skill / stat points notification on Hero button. Maybe right for stats and left for skill points

a simple button to allow going to the map while fighting instead of having to go to town and then to map or waiting till round is over

display the drop chance of items when hovering them in map stage section

either current should be retried on death
or put back to last successful complete with retry on



dragging ring from inventory to bottom ring slot replaces top ring slot
Achievement categories shows that it has one to claim even if not after first unlock and claim fixed on game restart
skill tree and Artifacts page shows tutorial button but nothing happens
on game startup game sound settings are ignored (on GameForge screen sound is played)

Hover over empty inventory slot press and hold shift move mouse over item click. Nothing happens.
a normal click on some items is enough to lock/ unlock
solution:i would maybe put it on ctrl click so it doesn't overlap with comparing items.



tutorial for new difficulty gets played again on tier 2 and 3
boss timer stops / sets timer to 0 on stun

Game seems completely unbalanced.
First nothing matters from Tier 0 to Tier 2 and from Tier 3 you can do nothing, since you need lvl 300+ equipment but only get up to lvl 200 equipment from the mobs.
Vitality build seems the only viable one since your companions dmg relies on it and it makes you survive longer so you basically get 5 in 1.
I tried a strength build as far as i could but it wasn't even 1/10 of the damage i did before.
Mix of both might be best.

Fire Mages skills are more than 10 times stronger than the others

For a Skill i will only name one op and one weak example
Healing well outheals the damage of every normal mob
experienced collector the mob (Jungle Temple Tier 3) gives me 7500xp but 6,24 million gold so 7500*5=37500 extra gold who in their right mind would waste a skill slot for that ? It's like a 0,6% increase