Some tools you can use to get started on your project for Ludum Dare 47:

Game Engines: Unity, Unreal Engine, Scratch, GameMaker, Core, Godot, Cocos Creator, Construct

Sound Effects: bFXR, Leshy SFMaker, sFXR, GarageBand, Ardour, LMMS, Audacity, BeepBox, CGMusic, Chiptone, Ableton

Art/Assets: Krita, Blender, GIMP, Aseprite, Clip Studio Paint, Piskel, Photoshop, Procreate, GraphicsGale, Paint.net, Pixelorama