1.12 things you need to know before playing
Combat system, I'd seen a lot of players say "I don't get the bar thingy" so to those who don't know what it is. The bar is how long until you can attack again if you try attacking g before that (I ran tests) if you spam it you will only do 0.1 heart of dmg. If you let the bar go half way it will do half the weapons damage. So it's best to wait for the bar to regen before hitting.
Offhand, the offhand is great for multi tasking such as placing blocks, eating, using shields, rockets, also it's great with dynamic lights for caving!
New items, there is now new items such as elytra, lantern, lingering pots, chains, iron nuggets, shulker boxes, shulker shells, chorus fruit, new arrows, and etc.
random stuff. You're able to force yourself into crawl mode with a fence gate or trapdoor (idk if the trapdoor method was added in 1.12 but it might have been added in 1.13.) Woodland mansions are around now (I think.)
More updates soon (I am gonna looks for good seeds, or speedrunable seeds.