Ludum Dare is a great place to know more tools for game development, so I’d like to share the tools I used to make Micro World.
Flixel - Open source game-making library for ActionScript 3.
FlashDevelop - Open source code editor. Supports ActionScript (2 and 3) and haXe .
GraphicsGale - Animation graphic editor. Good for pixel art.
Guitar Pro. Tabulature editor software. I used it to write the song and export it to MIDI.
GXSCC - Automatically converts a MIDI to 8-bit chiptune. Just drag and drop your MIDI to this window, then click Authoring to export it.
Bfxr - Generates manipulable sound effects with 8-bit style.
Free Audio Converter - I used it to convert WAV to MP3.