XPEssence is a mod for Minecraft 1.9.4 adding multiple new items, blocks and mechanics based on experience (yes, that green bar with levels on it).

I will use this mod to discover and experiment with Minecraft modding, but I hope it will be also as fun as possible to use.

How to get started?

Starting with XPEssence is quite easy. Your first goal is to find some Experience Gems. And fortunately for you, they just drop from random mobs ! So let's loot three of them. The next step is to cut some grass to find Devitalized Seeds. One is enough. Once you have acquired these two type of items, you can build an Experience Infuser. This looks like a furnace, but it will use Experience Gems as fuel. Put you Devitalized Seed in the top slot, and one gem in the bottom slot to infuse your seeds into Experience Seeds. You can now start to grow some Experience Gems (on regular farmland)!

Items

XP Gems XP Gem is similar to the "Bottle o' Enchanting", and will give experience to the player when used
XP Apples Same effects as the XPGem, but also restores a bit more hunger than an apple
XP Seeds This will allow you to grow XP Gems like any other plants. These grow on tiled dirt, and can be boosted with bonemeal.
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Blocks

XP Gem Blocks Combine multiple XP Gems to get a block. It can be used for decorative purpose, provides some light, and will also act as bookshelves to improve an enchanting table.
XP Gem Glass and glass panes Just some decorative glass
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XP Essence