Coins and Scrolls: OSR: Rhythm Dungeon (Crypt of the Necrodancer)

"Gimmick" dungeons are fun and classic. The dungeon is underwater! Gravity is reversed! You've been shrunk / it's built for giants! But I don't know if anyone's ever done an OSR Rhythm Dungeon.

Step 1:

You'll need a tablet/phone and speakers.
You'll need a dungeon map.
You'll need about 50 tokens. Glass beads, pennies, or poker chips work.

Step 2: Choose Music

The video game Crypt of the Necrodancer is the obvious choice. It's the game that inspired this post. If you're into rhythm games and/or roguelites, it's worth checking out.

Anyway, you need to pick:

I) Background Tracks: Stuff you can loop during exploration and other activities that don't involve too many dice being rolled.

II) Combat Tracks: Solid beats you can use for encounters. Each enemy type should get its own track.

III) Misc. Tracks: Chase scenes or other events that require dice to be rolled but don't involve combat directly.

I've listed some examples at the end of this post. Finding tracks is tricky. They need to have a strong metronome-like beat, they need to be loop-able, and they need to be thematically consistent so you can jump between tracks as needed. If you have suggestions, post them in the comments.

Step 3: Invent a Reason

Example 1:

Thactophalanic the Arch-Lich was once, in part at least, a High Elf. She demanded beauty from the entire world. Her once-elegant castles of gossamer and silver are tangled wrecks, but some of her more eccentric constructions carry on.

The Well-Tempered Halls contain the tombs of her most beloved musicians, dancers, and gymnasts. Sometimes she had them killed immediately after a performance to ensure the memory would never be tainted by some ungainly future action. The Halls are under a powerful enchantment. Only elegant, rhythmic movement is permitted. Combat becomes a ballet. Walking become a waltz. Music, eerie uncanny music, plays constantly. Needless to say the perfect instruments and gem-encrusted trinkets dragged from the Well-Tempered Halls have made many adventurers rich, but for every person who returns, the Halls claim ten.

Orzhov Guildmage, Greg Staples

Example 2:

Baron Dorian von Koss has invited you to Castle Rippenoft for an All Gallow's Eve ball, with music provided by a ghostly orchestra. It's sure to be the night of your life. Unfortunately, your invitation to dinner was literal. Can you loot the place and escape before the Baron and his fiendish vampire court drain your blood?

The Fearless Vampire Killers. This scene, but for the entire dungeon.

Step 4: Mechanics

The enchantment starts at an arbitrary doorway in the dungeon. Until that point you can move normally, although you might hear faint music. Across the doorway, movement becomes... stiff. It's like the air becomes as thick as mud off-beat. If you aren't expecting it, the effect is jarring. You have to move in hops and sways. Any action becomes a dart-pause-dart motion.

The music is soothing to creatures accustomed to the dungeon. They move in perfect patterns, elegantly stepping backwards and forwards, swinging their weapons or casting spells in lockstep. Interlopers are not so lucky. If they act "off-beat", the music actually hurts them. You can die just by being clumsy.

New Rules:

If you roll 2 odd numbers on the same turn, lose 1 HP. This only applies to PCs and hirelings. Only the first 2 odd numbers count, but they count on any dice rolled (damage, skill checks, HP gained from leveling, etc.)

PCs and hirelings have a pool of "Dance Points" equal to their Dexterity. They can spend these Dance Points to modify the number rolled any dice by +1 or -1. You can spend as many points as you'd like on any given roll. This doesn't count as modifying the roll for the purposes of critical hits. You can't adjust the number to more than the dice could possibly have rolled (an 8 on a d6, a 24 on a d20). You need to spend the points immediately after you roll.

Obviously, high Dex PCs have a significant advantage. That's fine. This is a gimmick dungeon.

You get your Dance Points back when you leave the enchanted area or whenever you pass through some arbitrary section, arch, or doorway into the next area. So you might have 12 points going into the Long Flute Mausoleum, spend 5 of them, and then reset back to 12 when you enter King Konga's Arena.

If you've got a Bard class in your game, their abilities might grant everyone else extra dance points.

Step 5: Plan Ahead

This is a gimmick dungeon. Use it for more than 2 sessions and it'll get tedious. The dungeon map should have lots of loops, a few boss fights (with silly names) and ludicrous magical treasure.