Game Design: The Binding of Isaac

In hours, I have played more of The Binding of Isaac than any other game in my Steam library. Edmund McMillen said he wasn't expecting it to be a hit, and has since proceeded to be proven thoroughly wrong.

It is kind of a big deal among a certain crowd: as I'm writing this, the second season of the Binding of Isaac Racing League, hosted and commented by Crumps, is in full swing - even though the game was certainly not designed for that!

There are many things that make it a good game. But one thing in particular stood out for me, that makes it extremely beginner-friendly.

About interactions

Perhaps the most important point in Isaac's design, and in pretty much everyone of Ed's games, is that the interface of the game is really simple, making it very easy to pick up (and yet hard to master). I'm not only talking user interface elements here (although the game HUD is remarkably sober), I'm talking interactions.

The whole game revolves around shooting and moving around. There is no mode for buying stuff. No mode for gambling. No mode for changing items or managing your inventory. No upgrade screen where you get to choose your upgrade on level up (nor is there levelling, by the way).

Each slot (except for trinkets, which are passive) are assigned one key: space for re-usable items (with the exception of forget me now), Q for rare consumables (tarot cards, pills), Ctrl for bombs. The rest of the game is controlled by walking into stuff.

Want to open a locked door? Walk into it - if you have a key, it'll open, otherwise, it'll act as an obstacle. Wanna gamble? Walk into the machine, you'll spend a penny and make it roll. Wanna buy an item? They're all lying on the ground, just walk into them. Wanna choose to go either to Sheol or to the Cathedral? Walk into a hole or into the holy light.

Compare this with Resident Evil 4, arguably a very different game, where the items you can carry around (grenades, weapons, ammo) are limited by the number of squares they take on the rectangle grid that is your inventory. Arranging them neatly is an important activity in the game, it is a full part of it, and it is, interestingly, a crucial point where speed runs can be improved.


There are many other reasons why The Binding of Isaac is an awesome game. It is a roguelike with an important random factor, it is strongly themed and very consistent, it's just plain ol' fun. But I wanted to focus this article on interface simplicity, which can reveal quite challenging to get right for budding game designers, like yours truly.

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