A practice tool for lead guitar
Murrsick

Learn a song by its numbers,
so you can play lead over it in any key.

The problem it solves

Context

A guitarist on stage doesn't need another chord sheet. They need to know what to play over the part that's happening right now.

Existing tools chart songs in fixed chord letters. The moment the band starts a song a whole step down, that chart is the wrong document.

Real situations

Improvising softly behind a sermon close, in whatever key the backing track is holding.

Real situations

Moving the congregation from one key to the next, song to song.

Real situations

Remembering a song as "the chorus is 1 5 6m 4" — and knowing how to solo over it.

Everything is stored as numbers

The core idea

Murrsick never stores chord letters. A song's progressions live as Nashville scale degrees — relative to the key.

Stored on disk · never changes
156m4

Because the degrees are relative, the same song map is instantly correct in every key. Key-independence is structural — not a transpose button bolted on afterwards.

Change the key, not the song

Why it matters
C
1C
5G
6mAm
4F
→
E♭
1E♭
5B♭
6mCm
4A♭

One field changes. Every chord name, every suggested scale, the degree strip and the fretboard diagrams all re-derive at once — because none of them were ever written down.

One song, studied from the centre out

The Song Canvas
Utility bar

app menu · tempo & metronome · key pad drone · key · theme

Degree strip
12m3m 456m 7°

the seven in-key chords, always visible

Structure

Sections as ordered number maps. Selecting one makes it active.

Song
title · artist · key
146m5
Arpeggios
Chart
Scales

What fits over the active section — plus the neck and the target tones.

Structure — the spine

Module 01

The song as an ordered list of sections, each one typed as space-separated number tokens.

Add, rename, reorder, delete. Selecting a section makes it active — and the active section drives the centre display, the Scales module and the Arpeggios neck. Every other module is a lens on it.

Verse
1415
Chorus · active
156m4
Bridge
6m415

Scales — what can I play over this?

Module 02

For the active section, Murrsick ranks the section-wide scales that fit the whole progression, then the per-chord choices for each chord in it.

Over the whole chorus
C MajorC Maj Pentatonic
Per chord
C · IonianG · Mixolydian Am · AeolianF · Lydian
C Major on the neck
Root Scale tone

Arpeggios — the notes to land on

Module 03

Strip the scale away and show only the chord tones, labelled by interval. It teaches you to spell a chord on the neck and to target it, instead of running a shape.

Chord tones · Am
RA
♭3C
5E

Pick from the active section, or from the key's diatonic set

A minor triad on the neck
Root 3rd & 5th

Chart, time and drone

Module 04 + utilities
Chart

Personal notes, not a chord sheet.

A capo value plus free text — key-change plans, how to sing a line on the guitar, tonal choices, the quirks you keep forgetting.

Metronome

Time at the song's tempo.

Multiple click and feel modes, adjustable volume, and beats-per-measure under the hood.

Key pad

A drone in the current key.

Hold a key between songs, or play softly over it behind speech. It follows the song's key automatically.

What the engine computes

Under the hood
01

Resolve & transpose

Any number token to a real chord in the key — 6m → Am in C. Degree-preserving across every key.

02

Diatonic sets

The seven chords and numerals of any major or minor key, plus chord tones for each.

03

Scale library

Twelve scales — modes, harmonic and melodic minor, both pentatonics, blues — filtered for relevance to the key.

04

Capo ↔ shape family

Which open-chord family a capo position gives you, and the capo that gets you back to a family you like.

The point of all of it

Numbers in,
fluency out.

Understand the song well enough
to stop reading it.

Murrsick 1 / 11
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