You don’t have to buy next week’s Destiny expansion, “The Taken King”, to check out some of the big changes it’ll bring to the game.

A ginormous patch goes out today to brings Destiny in line with everything that’s being altered in “The Taken King,” and it’s a laundry list of new adjustments. Just about everything is on the list: the three main player classes, a ton of the game’s current weapons, several game modes and even how you acquire and save weapons and other items in the game is now different. You can see the full list of changes here.

Many of the updates are pretty granular, changing the stats of weapons from the first year of the game to bring them in line with developer Bungie’s plans for the future. But a few of the alterations will be expansive—for one thing, all the missions from Year One are being migrated to the game’s new “Quest” system, which changes how you’ll work through the game’s story content.

There’s also a chance to check out some new content from “The Taken King” ahead of its launch, and without having to pay for it. For the next week, you can try all eight of the expansion’s new competitive multiplayer maps, as well as its two new game modes, “Rift” and “Mayhem Clash.”

It’s a good week to play Destiny if you’re looking to see how “The Taken King” is going to affect things, and maybe even to determine whether it’s worth your $40 come Sept. 15. It might also give you a sense of how much “The Taken King” is going to ruin your favorite guns.

Just watch out for the 18GB update you have to download first—maybe head home on your lunch break today and make sure it’s started.