Solid and polished game. I like your use of the brain hemispheres for the UI, though each side could use a label or symbol for clarity. Your use of a time limit on controlling the thoughts and having ranged and "melee" versions are good choices.
If you decide to continue working on this: since it's "all in your head" I think you should aim for wild visuals for the background, and give the thoughts more varied art and attack styles.