I can tell you put a lot of work into this game, it's a really cool concept! The music, art, and sound design are all really cool and match well! The minimalist style of the game combined with its gameplay make for a really cool aesthetic! I can't wait to see what comes of this game!
My only gripe is having Middle-Click be the delete key. Why not just make Right-Click the delete key and have it so dragging the edge of an action (with Left-Click) changes its duration?
Other than that small thing, great game!