Hello, played Flare for few hours, didn't finish it yet, but here some feedback:

1 More scaling and resolution options needed. I eventually found way to change it in config files but 640x480 by default is just very uninviting in 2018. Even Diablo 2 had 800x600 mode :)
Default probably should be something like 1280x720 considering how common widescreen resolutions are now, with various options like filling whole screen, 2x / 3x / 4x scaling modes, etc

2 If player uses skill bound to left / right mouse buttons but has no mana or skill is on cooldown use basic attack instead. Replacing default attack with something more powerful and relaying on mana regen items is common tactic in modern arpgs.
At the moment when you are out of mana you hero stops doing anything which kills pacing.

3 If "move using mouse" is enabled and you click and hold mouse button on enemy character should run to melee range first before attacking. Current behavior is very clunky for melee characters.

4 HSL shift to increase enemy / item variety? Recolors were used a lot in Diablo 2 to make new monster subspecies / champions, I think it's great way to increase variance with limited visual assets.