Futuristic Age

The Futuristic Age is the sixth Age encountered in the game. Multiple ores are revealed in this Age, including Diamond and Emerald. Some of the new tech includes crafting Creative items, which when crafted will lead to the Creative Age, the final age in the game. The Creative Age shares a tab with the Futuristic Age and is triggered when you craft an Ultimate Crafting Table. The previous Age is the Modern Age.

Materials
Diamond and Emerald become available in this stage, as well as Uranium and Osmium in the Overworld. Dimensional Shard Ore becomes available in the Nether. The easiest known method for finding diamond is to explore a desert with a slime sling and a Traveller's Cloak of Slow Falling. If you have a stable source of energy at this point, you can construct an Environmental Tech void ore miner with an appropriate lens to drastically speed up collection of any rare ore. In fact, it is not necessary to find emerald to do this. Osmium is highly useful for it's purposes in Mekanism tech, and is easily found while searching for diamond. Uranium currently has no known use.

Each planet will also have it's own resources available for collection, which are necessary to build the next tier of rocket. A deconstructor is recommended to at least salvage some of your parts from a previous rocket.

The asteroids are the big difference here in that they aren't one specific planet but a large space of asteroids. Each large asteroid may (not guaranteed) have a large cluster of ore in the middle of it: to progress you will need to find one of these with Titanium ore. Good luck. While you're at it, try to find a diamond asteroid to solve your diamond use for good.

When you finally make it all the way to Saturn, collect some green looking surface rocks (which is actually slime ore) using a silk touch pickaxe and blast it in an atomic reconstructor to get inferium. 8 of these will do nicely. Throw these in a cloche and start pumping out tons of inferium - you'll need it later. After you make it all the way to Neptune, grab some zinc ore and use an empowerer to make some prosperity shards. A stack of the Neptune Zinc is advisable. Now you can start on mystical agriculture!

Mobs
The only new mobs encountered are those in space: Evolved creepers, skeletons, zombies, witches, and endermen. Beware lightning storms on Jupiter as they will create many very strong evolved witches. All mobs now have a 50% chance to spawn with a diamond sword and 50% odds of any amount of diamond armour. Boss mobs will also be encountered in all the planetary dungeons. These are:

Mercury: Magma Boss

Venus: Spider Boss

Moon: Skeleton Boss

Mars: Creeper Boss

(and more...)

All the dungeon boss mobs can be avoided through use of the Scamulator, an ore/block from the respective planet and cheese from the moon to create the next schematic.

Energy
Hmm. How to get energy. That is the question. At first, a few fluid and solid combustion generators will do, but they quickly fail to produce the needed power. A galacticraft solar panel may also suffice for a bit at around 40 RF/tick but will quickly fail to provide necessary outputs. One known technique of producing vast amounts of power is the Environmental Tech Solar Array, which provides over 200 RF/tick at it's most basic model. If you will go long periods of time without using power, consider investing in a few Mekanism Energy Cubes to save up. If you go this route, consider using cups of coffee in a culinary generator - each cup will produce over 1 million RF in total. Eventually after reaching mystical agriculture you will be able to grow dragon eggs, which each provide over 2 billion RF.