Smash & Grab: the first team to collect ten crystals - and hold onto them - wins the game, all while fighting against your opponent team, of course.
Bounty: you need to collect stars for your team by taking out your opponents, but remember you're fair game to the enemies so watch your back. The team with the most stars at the end wins.
Heist: crack the safe protected by your opponents/defend your own precious safe. You've only got two minutes to try to rob the loot or to defend your own.
Showdown: the biggest rumble of the lot. Ten players are dropped into a slowly shrinking area and you've just got to be the last person standing.
Collect Coins, Elixir, and Chips to upgrade/unlock your brawlers, and you can band together with other players to play together and share strategies (not with the opponent team, obviously).
There's a livestream going on at 5 PM BST, so make sure you check that out to see what Supercell's got in store for us.