Team Fortress 2/pl goldrush

Goldrush is a popular payload map which is so far the only one of its type.

Pushing the Cart
When your team is on the offensive, the goal is to "push" the cart on the tracks from the starting point to the enemy base. You push the cart by standing close to it. The cart heals members of the offense as they stand by it, making them less easy to kill. A good idea is to always keep moving when you're near the cart to avoid sniper fire, etc. Scouts, Snipers and Heavies are classes to be concerned about. The Scout can rush in and attack quickly, the Heavy can mow down all your teammates around the cart, and Snipers can pick all the support of the cart off one at a time.

Defending
When your team is defending, the goal is to keep the other team from "pushing" the cart to your base. I'll map out what each class should do to help.

Soldier: Stay out of sight and turn corners to shoot multiple rounds quickly, then duck back to reload. As a soldier you're an easy target for the cart's support, but the splash damage can injure or kill the enemies pushing the cart.

Scout: Rush in quickly to take out enemies with your scattergun, then swiftly retreat back to a healthpack.

Engineer: Construct dispensers out of sight near the tracks so your teammates can heal and reload quickly without having to retreat much. Construct sentries in regular strategic sentry spots, just make sure you stay near to repair it, as it will get damaged.

Sniper: Stay in spots with minimal amounts of your body showing. Your main target is of course the cart, so you don't need a wide range of sight, meaning you don't have to expose your body much. I cannot stress enough that you must take out Heavies and Medics, because Heavies are great at clearing the way for the cart, and Medics will keep the cart moving by healing the pushers.

Medic: Uber Pyros as much as possible. Nothing is more effective than an uber Pyro and Medic rushing the cart, lighting everybody, and pushing back the enemy.

Pyro: Rush the cart on "suicide missions" essentially, which can end in you killing several enemies. It's good to become used to rushing in and out getting damaged as little as possible, but this takes a lot of practice.

Demoman: Sticky the cart as much as you can, especially before the match starts. Also, sticky the choke points that the enemy comes out of to push the cart.

Heavy: Turn corners to mow down the enemies on the cart, but don't center yourself on the map. Preferably be getting healed by a medic while you attack.

Spy: Usual spy tactics.