The environments are the levels in Risk of Rain 2. Currently, eight main levels exist, as well as three secret ones.
The following may contain spoilers!
The combat environments consist of eight different settings, with one of two alternatives being available for the first four stages. These settings are selected when the teleporter is activated, and may change during the run. (ie.the first time around level one may be Titanic Plains, and looping may take the player to Distant Roost)
A cliff overlooking a sea, or a lake, with multiple islands visible in the distance. One of them is sometimes accessible. The area sports some trees, and sometimes Shrines of the Woods.
Large, passive, dragonfly-like creatures spawn in this map. They fly far above the other islands, and can generally only be hit with long-range attacks. Shooting and killing them does nothing.
A large plain, bordered on one side by a high cliff, on the other by a steep drop. This area features multiple different-sized stone rings.
A mire, featuring large, fallen trees. Ruins of walls and other buildings litter the watery level. The Altar of N'kuhana is located underneath the map, accessible through the hole in the cliff, under the stone walkway.
"Origin of Tar"
A desert with remains of aqueducts and bones of massive animals. Going beyond the line of flags that border the desert will result in tar starting to attack the player. A hidden path, closed by an ancient gateway, is located here. The gate can be opened by pressing the hidden stone buttons placed in random locations on the map.
"'UES Contact Light' Survivor Camp"
One of the two possible third stages, this arctic stage seems to be the crash-site of at least some of the containers from UES Contact Light. A cave is located in the wall surrounding the map, and an island can be seen in the distance.
Though it may seem to be accessible by hopping from container to container, it is currently unreachable.
The Timed Security Chest always spawns somewhere on this map.
"The Wisp Sanctuary"
One of the two possible third stages, this garden-like stage with multiple tiers is located in a forest.
The Grovetender may serve as the boss on this stage.
A hellish underground stage, with glowing crystals and massive chains. This map has a long cave inside one of the walls, and multiple platforms above the ground level. The platforms can be reached by walking along the chains, or by walking into the steam vents.
Legendary Chests first spawn here, each yielding a Rare item. There is always one hidden beneath the large stones, underneath the highest platforms, and sometimes others in random locations.
The character REX can be found on one of the platforms. Bringing a Fuel Array from an escape pod will complete the power plant challenge and unlock Rex.
One of the two possible fourth stages, it is a dark, gloomy graveyard of ships and mechanical parts. Within the map is an underground cave system and an array of spherical machines. There are random containers hanging from random areas. It is also littered with mushrooms and eggs
5-6 or more eggs can be found around the map and broken. If at least 5-6 eggs are broken then an Alloy Worship Unit will spawn. If killed the boss will drop a Rare item for each player.
A fractured level filled with Easter eggs. The location of the Obelisk, necessary for unlocking the Mercenary. Accessible through the Celestial Portal, which spawns when completing the third level more than once.
A secret level accessible only through obliterating at the Obelisk while having a Beads of Fealty in your inventory. The level contains a secret boss arena where you fight one of four Twisted Scavengers. After defeating him, he drops 10 Lunar Coins and the run ends.. If you die during the Twisted Scavenger boss fight on Monsoon you won't get any mastery skins.
A secret boss arena, accessible by donating money to a randomly spawning Altar of Gold and entering the Gold Portal. There is also a small chance for it to be purchasable as the next environment in the Bazaar Between Time.
An environment where you fight the Artifact Reliquary to unlock Artifacts. Accessible via the teleporter under Sky Meadows. A combination (found on stone tablets around stages) is required to open a portal. You get a different Artifact depending on which combination you enter to spawn the portal.
A secret level, accessible through a portal beneath the Bazaar Between Time. The level contains nine Cell Vents, which are similar to the Teleporter Zone in classic combat levels. The player must charge all nine cell vents while monsters spawn and are rewarded with an item of an increasing rarity for each charged cell.