This game is interesting to me in a lot of ways. Here's some things I noticed:
When I ran to one side, attacked and mid attack pressed the button to go to the opposite side, the character would stay locked in place after the attack for a couple of seconds before moving. That could get you in some nasty situations if there were more enemies.
I also noticed that, when attacking the enemies from a certain distance, they'd stay still in place for a short while like they got stunned, which is fine. However, when they got attacked whilst being a little closer to me, they'd still go after me whilst being attacked and would end up damaging me. I'm not sure if that's intentional, so I thought it'd be worth to point it out.
As people have stated, the control scheme can be quite tricky. An idea would be maybe to, instead of pressing E or Q multiples times to get the color you want, use E or Q to select the primary or secondary color slot, and use the mouse scroll to scroll through the color options of the primary or secondary slot. Maybe for unequipping, double right click? It's a possibility, though I'm unsure how that would be properly translated to keyboard only, gamepad or even touchpad for that matter.
Alternatively, you could make a hotkey to mix between Primary/Secondary Color Mode, and Mixed Color mode, with the same idea of using mouse scroll to go through colors. Though, that would take away from having the player learn and handpick the different color combinations. Just throwing some ideas out here, maybe they'll spring a new idea for you.
I like the different concepts of this game. You can make so many things with this! Certain projectiles that can only be blocked by swinging a certain color, platforms that the player can only stand on when having a certain color on their brush, attacks that the player can dash through safely when having selected a specific color. I really like the idea of the area's color being restored, and it'd be interesting to see that in more complex environments. Imagine a forest receiving that treatment, for example!
The spritework's nice and is able to convey very clearly what's happening. I also really like the design of the main character! It's simple and yet has quite a bit of character.
The boss is an interesting concept to show a little of what the game could do, and I don't think there's much I can say about it without boiling things down to the game only having 2 weeks to be developed. I think there's a lot of potential you can tap into with this and I enjoyed my time with the game. Really nice work!