First map created by Uncle Acid bt_octogon_beta is a chest capture map with the knights located in the middle castle and the side islands. The Vikings and Pirates each have a tower with a chest capture zone and a dock to board the flying ships. There are two chests located in the middle castle and 1 on each side. Knights can spawn either in the middle castle or on the side posts. Each of these knight towers is a capture zone. To get into the middle castle, the doors must be broken (and they are sturdy). Food, armor, and ammo can be found around the map. Knight strategy: Archers should stay on top of the middle castle and shoot invaders. Heavy knights should stick to the bottom level guarding the stairs. Man at arms and additional archers should guard the side posts.
Pirate and Viking strategy: Divide and conquer, but remember to stick with your group. The knights will be spread out defending, but they will respawn near by. Throw chests off of towers or quickly jump onto ships. Just make sure the ship is going in the right direction ;). If either the vikings or pirates have most of the chests, use the ships to your advantage. Get a special, grab a chest and run either to the ship directly, or go down the stairs, jump off the bridge, run around the land, and catch a ship on a side post.
It's not supposed to be easy. Thank you and have fun!