Solar System

Solar System is challenge #6. Isaac starts this challenge with Distant Admiration, Forever alone, Halo of Flies, and Transcendence. Isaac will also be blindfolded. The goal is to defeat Mom's Heart. This Challenge is available after unlocking Transcendence.

Difficulty

As Isaac is blindfolded, Isaac cannot use tears, and must rely entirely on Distant Admiration, Forever Alone, and bombs to deal damage.

Strategy

Because Isaac starts with 3 Fly items, he will also begin the challenge as Beelzebub. This allows Isaac to amass a large number of friendly flies on the Basement floors.
The orbiting attack flies can be quite powerful, especially Distant Admiration when used properly. This will require optimization of Isaac's movement to maneuver into position to deal damage, as the flies are constantly moving, and avoid damage simultaneously.
- Duct Tape can fix the position of the flies around Isaac, somewhat alleviating this.
Enemies that explode on death should only be targeted with Forever Alone, as destroying them with Distant Admiration will result in Isaac getting caught in their explosions.
Shops can carry BFFS! and Hive Mind, the former of which affects the damage of the orbiting attack flies and the latter of which affects the damage of the blue flies spawned from Beelzebub as well as the size of the orbiting attack flies.
Broken Watch and Stop Watch are good items to buy since they slow enemies down.
Obtaining Gnawed Leaf makes the challenge trivial as Isaac's orbiting flies still deal damage while Isaac is invulnerable. Obtaining it is highly unlikely, however, since there is no treasure room present.
Obtaining Ball of Bandages or Cube of Meat grants a full circle of projectile-blocking orbitals around Isaac.
- Obtaining Book of Revelations makes The Harbingers easier to find, allowing Cube of Meat and Ball of Bandages to be found more often.
It is not advised to reshuffle Isaac's items. As this will not remove Isaac's Blindfolded status, it is possible to reroll items in such a way that the run can no longer be completed.
Obtaining the Rune of Algiz, Chaos Card or The Bible can make killing Mom and Mom's Heart/It Lives! much easier.
Devil room deals such as Brimstone, Maw Of The Void, and Mom's Knife will be ineffective, because of the blindfolded status.
- Maw Of The Void now functions despite the Blindfolded status, making this a very valuable item for the challenge.
The Boomerang is a useful purchase from the shop as it has a chance to freeze enemies, allowing Isaac to safely use the attack flies against them for the duration of the freeze.
Transcendence and other flight items are useless in this challenge because the Beelzebub transformation grants flight by default.
Obtaining Bob's Brain can be handy for defeating bosses, due to its damage and poison effect. It can also be used to break poop or golden poop to gain health, coins, or bombs.
Extension Cord electrifies the orbiting flies, dealing extra damage and destroys fireplaces and poops.
Black Powder helps damage non-flying enemies and bosses.
- Black Powder is now effective on all enemies and bosses.
Incubus acts as a replacement for Isaac's tears, thus indirectly removing Isaac's Blindfolded status.
Revelation can charge and fire regardless of the Blindfolded status, providing Isaac with an easy way to deal damage.
Pause can be used to almost guarantee victory as you can use it to stun all enemies in every other room. Pairing this with items that increase the amount of charges and you can assure victory.
If you see the Sacrificial Altar, do not use it under any circumstances. You will lose both fly familiars, and be effectively unable to do anything.
Collecting two cubes of meat grants you a tear-shooting homie.