I recently had an idea for a map where the payload cart moves on it's own, and Blue must defend it from being destroyed by the Red Team. After going through a few possible ideas, I ended up with one: The bomb moves through an area in some way close to the ground. It is followed by a capture area entity. Red must capture this area and hold it for an undetermined amount of time, so they can plant an explosive on the side of the bomb. If the bomb is not recaptured by Blue and the time limit is reached, the bomb explodes, causing red to win. Basically, Blue's objective is to protect the cart as it makes it's way through the level. At some intervals, instead of checkpoints, the bomb will stop, making it easier for the other team to capture. There's still a few things that need to be worked out, but I think it makes enough sense. The most important thing is whether to display the bomb's capture or it's path.