Old School Essentials is the gold standard of OSR today: the edition everyone writes to, even if they play something else at their table. It's the common language of OSR gaming.
Index Card RPG is the stripped-down street racing version of OSR. Gonzo, fast, and genuinely fun at the table in a way that makes it the obvious pick for a convention one-shot.
One game is the common tongue. The other is a joyride.
OSE
The design aesthetic is the first thing you notice. Readable, clean, and organized so that an entire race or class lives on a single spread. You don't hunt for information. It's just there.
Adventures and locations described in tight bullet points produce a specific quality of clarity that most RPG products don't manage. You can run from the page without translation.
If I were to start a new OSR campaign today, or go back seven years and restart my Hochheim campaign, it would be in OSE. That's not a small thing to say about a game when you've been running AD&D since 1979.
A magic-user, a cleric, and a ranger haggled with a goblin and a troll at the door to the Tower of the Winter's Daughter. They were trying to get inside to deliver a ring, to repair a wrong that had happened so long ago. That negotiation, measured and careful and charged with the weight of an old story, is what OSE produces at its best.
ICRPG
The target number by area mechanic makes running the game smooth in a way that's hard to appreciate until you've used it. One number. Everything in the room rolls against it. The friction disappears.
The practiced imprecision is the other great gift. A finger width apart. A finger length. Near. Far. Sketch the room on index cards and toss them on the table. No minis, no scatter terrain, no setup time. Just the fiction and the roll.
Both of those design decisions add up to the same thing: a game that gets completely out of the way and lets the chaos happen.
Three Erblin warriors and a human sorceress crawled down into the Old God's Hole. There was chaos. There was bloodshed. There was fun. At the end, they weren't entirely sure what they'd done. Then the Old God walked free to wreak havoc upon the earth. The table was okay with that. That's ICRPG working exactly as intended.
The honest case for the loser
ICRPG does something OSE doesn't try to do: it makes the table feel like a joyride from the first session. The target number by area, the practiced imprecision, the index cards tossed down in place of terrain: all of it adds up to a game that generates chaos and fun with almost no overhead. For a convention one-shot with strangers, ICRPG is hard to beat. The Old God walked free and everyone was okay with that. That's a specific kind of magic.
The pick
OSE, and it comes down to longevity. ICRPG is a great game for a session. OSE is a great game for a campaign, a shelf, a community, and a common language. The spreads, the bullet points, the clean design: all of it compounds over time in ways that make it the game you return to. If I'm going back to the dungeon for years rather than an afternoon, OSE is where I want to be.
That's my pick, and I don't think it was close. Prove me wrong in the comments.
If you're interested in seeing some of my OSR (and other) work, check out https://mountainfoot.itch.io/
