AHOD (All Hands On Deck) is a map and play-style originally created by trepan. It has since been updated by brad and now uses a plugin instead of a server mod. The aim is to get the enemy flag and a certain percentage of your team to the Deck to make a capture. The Deck is marked by an arrow and a flashing halo, as well as shockwaves on radar - you can't miss it.
You can be on either the Red or Green team, the blue team platform is the target Deck. Once someone is on the Deck with the enemy flag the plugin will announce how many more people on your team are required to make a capture. When the flag is captured both teams die and respawn at their bases.