Jonathan Blow on how movement works in his new game

Core concept: movement as transactions with commit timing

Jonathan Blow explains how his game’s movement system works “under the hood,” focusing on a transaction/commit model for player movement.

• Movement is represented as transactions. Each move transaction corresponds to:
  • a sequence of controller actions, and
  • a sequence of position/state updates.
• The UI/debug visualization shows state changes:
  • Yellow: a move transaction is created but not committed yet (the character hasn’t reached the target square for gameplay purposes).
  • Green: the commit happens around the midpoint crossing between squares.
• As successive move transactions occur, the system alternates yellow/green.

Why turning can feel “locked” (common player complaint)

If the player initiates a new direction while a prior move transaction is still pending:

• Even if the character is almost past the square center (“one iota past the center”), the character cannot turn immediately.
• Instead, the character must wait until the current move transaction commits, which may occur after the character has visually continued moving.

Example behavior described:

• Holding left continues the movement.
• Even if the player presses “up” while still mid-move, the character can’t begin north movement until the character is inside the square for gameplay purposes (i.e., after the commit).

Different feel depending on input style

Blow contrasts two input behaviors:

• Tapping / discrete presses (tap arrow keys / D-pad)
  • Avoids the issue more often, because the intended direction changes align better with transaction commits.
• Holding a key / analog stick and then pressing another direction
  • More likely to overlap with a pending transaction, which causes the “can’t turn yet” behavior.

Planned improvements

Blow says the next development task is to tighten up the feel of movement by allowing turns even if the character is over there (before commit), with conditions:

• Turning should be allowed once it’s sufficiently safe, as long as the movement isn’t a “gnarly transaction” with lots of changes happening simultaneously.
• He also notes this improvement will likely apply to analog stick movement on Switch, since the underlying behavior reportedly exists there as well.

Main speakers / sources

• Jonathan Blow (developer, primary speaker)