Repuzzle - a Pico-8 Coding Puzzle Game
Insert, replace, delete, and move characters to win over 22 levels, ranging from the simple to the tricky.
Explanation of the basic controls is provided in the game.
Tips:

The pico-8 manual and pico-8 wiki can be useful. (both for this game and in general)
If you're stuck on one level, try another. The different 'sections' each go roughly from easy to hard, with a lot of variance in-between.
If you're really really stuck, the hints can help.

Full list of controls:
Browsing:

Arrow keys to move between characters
Ctrl + Arrow keys to move between words
Page UpDown to move between pages
HomeEnd to move to startend of line
Ctrl + HomeEnd to move to startend of code
You can also scroll via Mouse Wheel and move to a character via left-click

Switching Mode:

Tab to select the next editing mode
Ctrl+123 to select insertreplacemove mode directly (can also use F1F2F3 in BBS only)
Clicking on a mode with the mouse will select it as well

Editing:

Type to insert characters in insert mode
Type to replace characters in replace mode
Backspacedelete to delete characters in insert and replace modes
Backspacedelete to mark characters for moving in move mode
Type to move marked characters in move mode
Shift + Backspacedelete to undo changes (in all modes)
You can type lowercase, uppercase (with Shift), digitspunctuation, and line breaks (Enter)
Ctrl + V to paste code from the clipboard (in insert mode only)

Running:

Ctrl + Enter to run the code (you can also use Ctrl + B or 'run' in the pause menu)
Escape to abort the run
Upon error or abort, Tab (or Ctrl+1..6 or left-click) to browse the stack trace
If the code did any drawing or printing, you'll also see a 'see output screen' option - browse to it via Tab(etc) to see the output

Misc.:

Ctrl + C to copy all code to the clipboard
Escape to acc

License: None (Free)