Planets

The Moon

Your first destination! (if you're playing survival) Not much is going on here in terms of wildlife. As for progression, you will need to search underground for a Lunar Sapphire geode, a large rock formation similar to Amethyst geodes. They can be farmed for Lunar Sapphire, which allows for more complex machinery.

With Glowstone Ore being found here, you also unlock higher tier potions.

Optionally, you can also search for an abandoned Lunar Base, which has a chance to carry the unique enchantment "Frostbite," as well as containing many useful resources.

For the time being, this is where progression ends on the moon. However, there is more planned for the moon and it's creatures.

Mars

The classic red planet is the next step in progression. Here, Mars' high iron content comes in handy. Deep underground, you can find Martian Iron ore, which when combined with volcanic ash and heated, it can be forged into Martian Steel, unlocking Temperature Regulators, Oxygen Detectors, the Electrolysis Machine, and more powerful space suits and tools.

You can also find abandoned Martian Bases, which can contain many valuable resources, as well as dormant Martian plant-life that can be resurrected using enhanced potions.

Here, you face your first formidable foe: the Echo Worm. The Echo Worm is completely blind, and can only detect you through sound. It is possible to go without fighting them for your duration on Mars, but that is easier said than done.

Additionally, the Martian Cobra can be found here. Less dangerous, but they can still pack a punch. They can be avoided entirely if you avoid looking in their direction.

Mercury

Mercury, being the closest planet to the sun, is extremely harsh and it's surface is completely sterilized by the heat. Though at night, it becomes extremely cold, where even liquid oxygen can exist on the surface. As such, most life resides deep underground, where conditions are more stable. Additionally, this planet's density and mass means that the next major resource, tungsten, is found here, deep underground.

Unlike the martian creatures, the next enemy will always attack. The Martian Raptor is an extremely clever creature, capable of opening doors, flipping levers, and pressing buttons. It will be hostile on contact, but it's sheer force is lower than that of the Martian Echo Worm.

Venus

Venus is an extremely hot environment, where even lead can melt. Venus is the only other terrestrial planet with a weather cycle, where sulfuric acid rain frequently pours down. Venus' extremely hostile environment makes competition fierce in the natural environment.

For the time being, there is no progression past Venus. There is more content planned, but currently, Venus is only for fun.

The Venus Stone bull is a large fungus eating herbivore, that will charge at the player if they get too close. Be careful not to get in their way.

The Mimic is a silicon based life-form, that will hide among the natural cave walls and ambush it's prey. Be careful to keep an eye out for it!

The Venus Scorpion is a hardy bug creature that uses the natural sulfuric acid in the atmosphere as a defense mechanism. If you get too close, it will spit it's acid at you.