The Planetarium is a type of room that is featured in The Binding of Isaac: Repentance, and players that want to earn all of the game's new achievements will need to unlock it. Fortunately, this is not an extremely difficult thing to do, though there is quite a bit of randomness to the process. Providing more details on that process is the exact purpose of this guide, and it will also contain information on how to find the Planetarium in The Binding of Isaac: Repentance after it has been unlocked.
Updated September 6th, 2021 by Russ Boswell: The Binding of Isaac: Repentance brought a lot of content with it. Players have put in countless hours trying their best and see and experience everything the full game has to offer. The Planetarium items are one of the cooler sets that made their way into the finished product. New players looking for how to unlock the Planetarium are likely overwhelmed by the newest mechanic. Thankfully the Planetarium in Isaac isn't too difficult to get once gamers understand what's going on. To help new and returning players experience all there is to offer astrologically, the following guide has been updated with more information.
How To Unlock Planetariums
To start, players will unlock the Planetarium after collecting three items from a designated pool of items during a single run. Specifically, that item pool is comprised of the 12 Signs of the Zodiac, the Crystal Ball, the Magic 8 Ball, and the Tiny Planet, and any combination of three is perfectly suitable. Upon meeting this criteria, The Binding of Isaac fans will receive an indication that they have unlocked Planetariums, and they will be able to encounter them in their runs moving forward.
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How To Find Planetarium Rooms
With respect to how to find these rooms, the initial chance of a Planetarium appearing is just 1%. However, every time that a player skips an item room in this new The Binding of Isaac DLC, that chance increases by 20%, and fans that are set on finding a Planetarium should thus bypass item rooms whenever possible. Notably, an item room is only considered to be skipped if a player does not go into it, and entering one but not picking up an item will have no effect on Planetariums.
Furthermore, a key is required to enter a Planetarium, and hopefully players will have one to spare when they come across the relevant door. Roguelike fans will know that they have found a Planetarium door if they see a crescent moon above it, and there is no real trick to entering it. Players that have a key should simply pass through the portal, and they will find a special astronomy item on the other side.
What Items Can Be Found In Planetarium Rooms?
Once players have access to Planetarium rooms, and unlock them, they'll be rewarded with an astrology/planet-themed item. There are 11 different items that Isaac and his crew can gain, each with its own useful modifier. Here's a look at all of the items that players may come across:
| Name | Quality | Effect |
|---|---|---|
| Saturnus | 1 | Players entering a room will gain a circle of tears that have a chance to absorb enemy tears and turn them friendly. |
| Venus | 1 | Players gain a single red heart container and will sometimes automatically charm enemies that are near them. |
| Luna | 2 | Each floor gains an additional secret room and extra secret room. Secret Rooms will then contain a special light beam that gives players half a soul heart and additional tears. |
| Mars | 2 | Players can dash by double-tapping a direction and become invulnerable during. They will also damage enemies. A small cooldown is applied to the dash. |
| Sol | 2 | Shows where the boss room is. If players defeat the boss it removes their curses, grants them additional luck and damage, and recharges their active item. |
| Jupiter | 3 | Players gain two heart containers. Isaac loses a small amount of speed (0.03) but will build up speed if standing still and can release a gas cloud when he moves. |
| Mercurius | 3 | Players will gain a small speed boost and all doors remain open even if enemies are around. |
| Neptunus | 3 | Isaac's mouth will now fill with tears. These tears will eventually stop and players can then hold the fire button to unleash them all at once. |
| Pluto | 3 | Increases Isaac's tears and makes him tiny. This small form allows him to move between objects and some enemy attacks will float over him. |
| Terra | 3 | Replaces Isaac's tears with rocks that do more damage, knockback enemies, and can also destroy obstacles. |
| Uranus | 3 | Gives Isaac Ice Tears that will slow enemies, freeze them, and cause them to explode into ice shards. |
Once a player has unlocked Planetariums, they should then feel free to move onto solving some of the DLC's other mysteries. Indeed, fans that want to fight the final boss and see The Binding of Isaac: Repentance's true ending have quite a lot to figure out, and that is not even the end of what the game has to offer. More specifically, there are a ton of character variants to unlock, and earning them all is certainly no small endeavor.
The Binding of Isaac is available on PC, Nintendo Switch, PlayStation 4, and Xbox One.
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