This is a really good game. Follows in the steps of titles like Depict1, and I've always appreciated games like these. It's not exactly original, but the concept is done well here. The pacing is a tad too fast at the beginning though; the player only has to wait for a few seconds before the narrator starts bringing the flag to them. I'd suggest giving it a bit more time for the twist to sink in.
My other complaint is about the boss: especially compared to the other flag trials before it (which are long enough to engage, but not too long as to become tedious), the boss is a SUPER long stage. It's the sole reason I haven't finished the game yet. Good on you for letting the player skip to the boss from the start menu, though. :)
Great job on this. You should seriously consider making this into a full-fledged game after the jam.