Decoding The Binding of Isaac: A Guide to Completion Marks

Introduction

Have you ever found yourself endlessly running through The Binding of Isaac, defeating the same bosses over and over, wondering why nothing new seems to be unlocking? You’re not alone. This game, a masterpiece of rogue-like dungeon crawling, can be incredibly complex and sometimes frustratingly opaque. A core component of progression, one that many players initially overlook, is the system of Completion Marks. These little icons, displayed on the character selection screen, are your key to unlocking the true potential of the game. They signify your mastery of each character and your ability to conquer the challenges The Binding of Isaac throws your way.

The Binding of Isaac, at its heart, is a game about repetition, adaptation, and discovery. Each run is a unique experience, with randomly generated levels, items, and enemies. This incredible replayability is driven by the constant pursuit of unlocking new content. Completion Marks are a vital component of this, unlocking fresh items, challenging new characters, and even branching paths that lead to alternative endings. This guide will provide a comprehensive overview of everything you need to know about Completion Marks, how to obtain them, and why they’re essential for truly completing the game.

What are Completion Marks?

In simple terms, Completion Marks are visual trophies. They are indicators on the character selection screen that show which major bosses you have defeated with a specific character. Each mark is unique, representing a different boss encounter. These marks are earned by successfully completing a run and defeating the boss at the end, and they serve as a roadmap of your accomplishments within the game.

Visually, Completion Marks appear as small icons arranged around the character portrait on the character selection screen. Each icon corresponds to a specific boss, such as Mom, Isaac, Satan, and so on. The presence of a mark signifies that you have defeated that particular boss with that character at least once. The absence of a mark indicates that you still have a challenge to overcome.

Completion Marks are vital because they act as the key to unlocking a vast amount of content within The Binding of Isaac. They unlock new items, playable characters, powerful trinkets, and even entirely new challenges that test your skills. Without actively pursuing Completion Marks, you’re missing out on a significant portion of the game’s content and hindering your ability to progress further. They motivate you to experiment with different characters, adapt to their unique playstyles, and discover powerful item synergies that can turn even the most challenging runs into victories. Mastering Completion Marks is essential for anyone who wants to truly conquer The Binding of Isaac.

A Detailed Look at Each Completion Mark

Mom

The first major hurdle for many players. Mom’s fight involves dodging her attacks from above and dealing with her relentless summons. To obtain the Mom mark, you simply need to defeat her with any character on any difficulty. Successfully doing so will often unlock basic items and lay the foundation for future runs.

Mom’s Heart/It Lives

This is a more challenging fight than Mom and involves a multi-stage boss battle. The first encounter is against Mom’s Heart, and subsequent wins will pit you against It Lives. It Lives is a much more aggressive and demanding version of the boss. Defeating It Lives unlocks several new items that can significantly impact your runs.

Isaac

This fight is found in the Cathedral, accessible after defeating Mom’s Heart/It Lives multiple times. Isaac is a challenging boss with a variety of projectile attacks. Obtaining the Isaac mark unlocks items and achievements that open up new strategies and build possibilities.

Satan

Found in Sheol after beating Mom’s Heart multiple times, this is a multi-stage fight against Satan himself. This battle requires good movement and understanding of his attack patterns. Obtaining the Satan mark unlocks powerful items, adding potent new additions to the item pool.

???

Commonly referred to as “Blue Baby”, this boss is found after taking a Polaroid or a Negative. Defeating ??? unlocks unique items and also achievements.

The Lamb

This hidden boss is found in the Dark Room after taking the Negative. This is a much more challenging fight compared to Satan and ??? and it unlocks a lot of valuable items.

Hush

The Hush fight is only available if you beat Mom in under 30 minutes. This is a difficult boss that takes place in a bullet hell arena. Obtaining the Hush mark unlocks items that can be critical for later, more challenging runs.

Mega Satan

Mega Satan is a secret boss that requires specific keys or items to access. This fight is extremely challenging and requires a well-developed build. Defeating Mega Satan unlocks powerful items and is a significant accomplishment for any player.

Ultra Greed/Greedier

Found in the Greed Mode stage, Ultra Greed is a challenging boss that requires resource management and strategic combat. Greedier mode, accessible through special conditions, makes the fight even harder. Obtaining these marks unlocks items and characters that enhance your economic potential in the game.

Delirium

This chaotic boss is found in the Void and is one of the hardest bosses in the game to beat. Delirium has the ability to transform into other bosses, making the fight unpredictable. Obtaining the Delirium mark is a significant accomplishment and unlocks potent items.

Mother

Mother is found in the alternate path by going down, which is harder to obtain. She is a difficult boss with attacks that deal a lot of damage. Successfully beating her unlocks new areas and characters.

The Beast

The final boss found on the alternative path going up, is obtained by defeating the four horsemen as they make their way to the beast. The Beast has multiple stages that require you to kill the horsemen, and then the final stage is the beast herself.

Tips and Strategies for Getting Completion Marks

Character selection is key to getting completion marks. Some characters, such as Isaac or Cain, offer relatively easy starts due to their starting items or abilities. Other characters, like The Lost or The Keeper, present significant challenges. Understanding the strengths and weaknesses of each character is crucial. Experiment to find characters that suit your playstyle and focus on mastering them before tackling more difficult options. A good rule of thumb is to learn the easier characters first before moving on to the hard ones.

Item synergies are the bread and butter of successful Binding of Isaac runs. Learning which items combine to create powerful effects can significantly increase your chances of victory. For example, Brimstone with Chocolate Milk creates a devastating, charge-based laser attack. Recognizing and exploiting these synergies is essential for overcoming challenging boss fights. Taking your time to learn which items work well together will significantly increase your chance of completing runs.

Effective gameplay involves a mix of dodging, prioritizing targets, and efficient resource management. Learn enemy attack patterns and prioritize taking down the most dangerous enemies first. Conserve your health and resources whenever possible. Utilize bombs strategically to open secret rooms or clear obstacles. Mastering these basic gameplay techniques will make your runs more consistent and increase your chances of reaching the final boss. Practicing movement is one of the most important things in the game.

Deciding when to play on Hard mode versus Normal mode involves a trade-off between risk and reward. Hard mode offers better item drops and the opportunity to unlock specific achievements, but it also increases enemy damage and frequency. If you’re struggling to complete runs on Normal mode, stick with it until you’re comfortable. Once you’ve mastered the basics, switching to Hard mode can significantly accelerate your progress.

Resource utilization is crucial, bombs, keys, pills, and tarot cards should be used strategically. Use bombs to open secret rooms or clear a large group of enemies quickly. Don’t waste your keys on unnecessary chests and save them for golden chests or special rooms. Learn the effects of different pills and tarot cards to use them to your advantage. Effective resource management can be the difference between a successful run and an early demise.

One of the most important things is knowing your enemies. Understanding their attacks and patterns will greatly increase your chances of getting completion marks.

The Road to Completion and The True Ending

Collecting all Completion Marks with all characters is a monumental task, but it’s the ultimate goal for many Binding of Isaac players. Achieving this unlocks the “true ending” of the game and signifies complete mastery of its content.

Some of the harder marks to obtain include beating Delirium with the Lost or defeating Hush with the Keeper. These challenges require a combination of skill, patience, and a bit of luck.

The final boss/ending unlocked after achieving full completion is a reward for your dedication. This is the pinnacle of the game, and it is proof that you have mastered the game.

Conclusion

Completion Marks are at the heart of The Binding of Isaac’s compelling gameplay loop. They provide clear goals, incentivize experimentation, and unlock a wealth of new content. This guide has provided you with a comprehensive overview of Completion Marks, including how to obtain them, and why they’re essential for truly experiencing everything the game has to offer.

Now it’s your turn! Use this guide as a roadmap to achieve your own completion goals. Experiment with different characters, discover powerful item synergies, and master the challenging boss fights that await you. Share your strategies, ask questions, and celebrate your accomplishments with the community. Happy hunting, and may your runs be filled with powerful items and glorious victories.