use WASD to move Red, and arrow keys to move blue. You will drop your flag if you are taged or moved too fast. You can tag enemies by touching them, you can't tag the enemy in their territory. Once your enemy dropped your flag, you can retrieve it by touching it. When you got your enemy's flag, run to the target looking thingy where you spawn. (TIP: you can get back the flag even at enemy territory by touching the flag part above your enemy)
Idea from a very old game that was played on playgrounds and used to be very populadr