How I beat challenges 4 and 5:
4. Let Shield follow Dragon, keep distance with Sword. When Dragon attacks Shield, close in with Sword (not too close, so you can escape when attacked), and attack Dragon.
5. Keep going from corner to corner. At the beginning, go into the top-right corner and go down from there. Try to stay as close as possible to the walls, but not too close, or else your robot will screw up when turning. They will hit you when changing directions, but you should survive it. Try to keep your red bar above their blue bar.
Rate + to bump this to the top!
Change your WINDOWS time to the next day, reload the page and you got the 'come back another day' mode unlocked. Don't forget to change your time back, or it will be weekend early! We don't want that now, do we?... Do we?
Reached 5.4 multiplier. The easiest game of all would be the blue vertical line jumping over the red circles. You can move as fast as the circles. Just jump over a few, move back when you reach the ground, and keep jumping over them and moving back.
Thanks :)