The Binding of Isaac: Rebirth Walkthrough — Start to Endgame

The Binding of Isaac: Rebirth is the ultimate roguelike for item synergy enthusiasts — over 700 items that combine in thousands of emergent ways, many of which the developers never explicitly designed. One run you're firing homing lasers, the next you're spawning an army of familiars, and the next you're a ball of knife-shooting orbital meat. The game's depth is staggering: 34 playable characters (including Tainted variants), 12 endings, secret floors, challenge runs, and an item pool so vast it takes hundreds of hours to see everything. The Repentance expansion is considered the definitive version, adding two new characters, hundreds of items, and the hardest content in the game.

This walkthrough takes you from your first session to endgame content. Each phase has specific goals, priorities, and milestones. Follow this path to avoid common traps that stall most players.

Quick Progression Summary

Phase 1: Getting Started — Basement

The starting floors (Basement I and II) with the weakest enemies and simplest room layouts. The treasure room on each floor contains a free item. The boss drops an item or provides access to a Devil/Angel room. Focus on building a damage foundation here.

Level/Difficulty: Floors 1-2 Key Rewards: Two treasure room items, boss item, potential Devil/Angel room access

What to Do in Basement

1. Learn item synergies. Items modify your tears (projectiles) in stackable ways. Spend your first session getting comfortable with this.
2. Pick Azazel as your starting build. It's the most forgiving option.
3. Tinted rocks (slightly discolored rocks with an X mark) always contain soul hearts, black hearts, or bone hearts when bombed. Learn to spot them — they're one of the most reliable health sources in the game.
4. Acquire your first equipment upgrade — Mom's Knife or whatever's available.
5. Clear all main content before moving on.

Phase 1 Checklist

• Understand item synergies fundamentals
• Azazel selected and functional
• Basement main content cleared
• Ready for Caves

Phase 2: Early Game — Caves

Floors 3-4 with harder enemies and environmental hazards (rocks, gaps). Secret rooms become more rewarding. The difficulty spike from Basement to Caves catches many new players off-guard. Tinted rocks (slightly different color) contain soul hearts when bombed.

Level/Difficulty: Floors 3-4 Key Rewards: Stronger items, tinted rock soul hearts, shop items

What to Do in Caves

1. Work on character unlocks. Characters unlock by completing specific achievements. This system becomes critical from here on.
2. Farm for Mom's Knife if you haven't already. It's the key upgrade for this phase.
3. Secret rooms always border at least 3 rooms (including non-accessible rooms). Bomb walls between rooms that share borders with many adjacent rooms. Use the map to identify the most probable secret room location.
4. Complete all objectives before pushing to Depths.
5. Consider whether Isaac might suit your playstyle better than Azazel.

Phase 2 Checklist

• character unlocks integrated into gameplay
• Mom's Knife acquired
• Caves fully cleared
• Ready for Depths

Phase 3: Mid Game — Depths

Floors 5-6 with dangerous enemies and Mom as the Chapter 3 boss. Reaching Mom within 20 minutes opens Boss Rush (15 boss waves for a reward). The Depths contain the highest concentration of locked rooms requiring keys.

Level/Difficulty: Floors 5-6 Key Rewards: Mom boss kill (required for progression), Boss Rush access, Polaroid/Negative pickup

What to Do in Depths

1. Master room clearing. Each floor consists of rooms cleared by defeating all enemies. This unlocks a new layer of gameplay.
2. Start working toward Brimstone. It's the best equipment and becomes accessible around now.
3. Devil Room chance increases with: no red heart damage taken on the floor (+35%), blowing up a shopkeeper (+10%), Book of Belial active. Angel Room chance increases with: donating to the donation machine, holding key pieces.
4. This area is the main skill check. If you can clear it, you're ready for late game.
5. Start investing in devil and angel deals for the tactical depth you'll need going forward.

Phase 3 Checklist

• room clearing mastered
• Brimstone acquired or in progress
• Depths fully cleared
• Ready for Womb

Phase 4: Late Game — Womb

Floors 7-8 with very aggressive enemies and Mom's Heart/It Lives as the boss. Reaching the Womb within 30 minutes unlocks the path to Hush — a bullet-hell superboss. The Womb is where underpowered runs typically fail.

Level/Difficulty: Floors 7-8 Key Rewards: Mom's Heart kill, Hush access (under 30 minutes), path splits to Sheol/Cathedral

What to Do in Womb

1. Finalize your build. You should be running Isaac or Azazel with optimized gear.
2. Brimstone should be your primary. If you don't have it yet, prioritize getting it.
3. Rerolling items with the D6 costs a full charge. Prioritize rerolling bad items in treasure rooms, Devil Rooms, and Angel Rooms. Don't waste charges on boss rewards unless they're terrible.
4. boss rush optimization starts here. Small improvements compound into massive advantages.
5. Farm this area for the resources needed to push into Sheol/Cathedral.

Phase 4 Checklist

• Build fully optimized
• Brimstone upgraded to max
• Womb fully cleared
• Ready for Sheol/Cathedral

Phase 5: Endgame — Sheol/Cathedral

Alternate final floors reached by defeating Mom's Heart. Sheol (accessed with the Negative) leads to Satan and then The Dark Room. Cathedral (accessed with the Polaroid) leads to Isaac and then The Chest. Each path has unique bosses, items, and completion marks.

Level/Difficulty: Floors 9-10 (alternate paths) Key Rewards: Satan/Isaac boss kills, completion marks, access to final floors (Dark Room/Chest)

What to Do in Sheol/Cathedral

1. Sheol/Cathedral tests everything. Come prepared with your best build and gear.
2. The Donation Machine in shops can be fed coins to unlock items permanently. At 999 coins donated, it explodes and drops rewards. Prioritize donating early in a run when coins are plentiful.
3. The endgame loop: run Sheol/Cathedral, optimize gear, push harder content.
4. Experiment with Tainted Characters for a fresh take once you've mastered the standard builds.
5. This is where boss rush mastery separates good players from great ones.

Phase 5 Checklist

• Endgame content on farm
• Best-in-slot gear acquired
• Sheol/Cathedral fully cleared
• Ready for challenge content

Common Progression Mistakes

• Taking every Devil Deal regardless of health situation — a 2-heart Brimstone is worth it, but a 1-heart Razor Blade when you're at 2 hearts total will end your run.
• Not learning to spot tinted rocks — these are the most reliable source of soul hearts and new players walk past dozens of them without realizing.
• Picking up items without reading what they do — some items (Soy Milk, Tiny Planet, Cursed Eye) can ruin your build. Read descriptions before picking up unknown items.
• Ignoring the shop — shops sell key items like Restock, The Compass, Steam Sale, and batteries for active items. Always visit shops when you have keys.
• Trying to 100% the game without external resources — The Binding of Isaac has over 700 items and thousands of interactions. The community wiki is an essential reference, not a cheat.

Key Tips for Smooth Progression

1. Tinted rocks (slightly discolored rocks with an X mark) always contain soul hearts, black hearts, or bone hearts when bombed. Learn to spot them — they're one of the most reliable health sources in the game.
2. Secret rooms always border at least 3 rooms (including non-accessible rooms). Bomb walls between rooms that share borders with many adjacent rooms. Use the map to identify the most probable secret room location.
3. Devil Room chance increases with: no red heart damage taken on the floor (+35%), blowing up a shopkeeper (+10%), Book of Belial active. Angel Room chance increases with: donating to the donation machine, holding key pieces.
4. Rerolling items with the D6 costs a full charge. Prioritize rerolling bad items in treasure rooms, Devil Rooms, and Angel Rooms. Don't waste charges on boss rewards unless they're terrible.
5. The Donation Machine in shops can be fed coins to unlock items permanently. At 999 coins donated, it explodes and drops rewards. Prioritize donating early in a run when coins are plentiful.

For detailed build optimization, see The Binding of Isaac: Rebirth builds. For quick wins, check tips & tricks.