It's a bit similar to the Payload game mode in TF2, which is completely fine by me because that was my favorite game mode. This has a bit more of a tug (or I guess push) of war aspect it, which could be really fun.
I was SUPER excited to hear that. In Payload, I had a fun time as a spy pretending to push but then killing everyone near the cart. Melee doesn't seem to be as strong for this for that purpose though, but I'm still super excited to play this!