In The Binding of Isaac, much like in any modern roguelite, the core gameplay loop revolves around you playing through the whole thing over and over, taking different routes and beating different bosses. When you’ve played a bunch, it can be kind of hard to remember what you have and haven’t done, but luckily, The Binding of Isaac has a system for that. So, what are Completion Marks in The Binding of Isaac?
What Are Completion Marks in The Binding of Isaac?
To help you keep track of the various unlockables, routes, and objectives in The Binding of Isaac, the game features Completion Marks, displayed for each character on the character select screen. Aside from a couple of exceptions, they’re all displayed on the little square note on the top-left of the screen.
Each of these symbols indicates a defeated boss or completed challenge found on one of the game’s various routes. If the symbol is solid black in coloration, that means you received it on the Normal difficulty. If it’s outlined in red, that means you received it on the Hard difficulty. Oh, and if you get a Completion Mark on Hard without getting the Normal one first, it counts for both of them. You already did it on Hard, what’s the point of making you do it again on Normal?
Completion Mark Meanings
Here’s which boss each of the Completion Marks corresponds to. Remember, 100% completion means getting all of these marks for every character in the game, regular and Tainted.
- Heart: Mom’s Heart or It Lives
- Cross: Isaac (Boss)
- Polaroid: ??? (Boss)
- Inverted Cross: Satan
- Negative: The Lamb
- Brimstone symbol: Mega Satan
- Star: Boss Rush
- Hush’s face: Hush
- Regular Cent sign: Ultra Greed
- Red Cent sign: Ultra Greedier
- Blood and tearing on the Completion Mark page: Delirium
- Knife: Mother
- Dad’s Note: The Beast
With a few exceptions, every character in the game unlocks a new item for the item pool by defeating specific bosses. These Completion Marks function as both progression trackers for your convenience, as well as reminders of which items you’ve unlocked without needing to check the full list.