Here are the list of most valuable game assets tools for indie game developers: Sprite Tools: Spine, Spriter/Brashmonkey, Texture Packer 2D Mapping: Sprite DLight Game Engines / Builders: Unity, Stencyl, Game Salad, Construct 2, Game Maker, Unreal, LibGDX, RPG Maker Image Editors: Gimp, Bloom, PixelMator Image Optimizers: PNGGauntlet, Tiny PNG Tile Editors: Tiled Audio Tools: Super Flash Bros, BFXR, Audacity, Free Sounds, Voice Acting, Audio Tool Source: Game Assets Tools and Resources
