MagicaVoxel - A free lightweight GPU-based voxel art editor and interactive path tracing renderer.
Unity - The multiplatform game creation tools for everyone.
Cubik Studio - Model in a unique cubic style. Start modelization with boxes. Move, rotate and scale cuboids.
Godot Engine - Feature-packed 2D and 3D open source game engine.
SpriteStack - 3D pixelart editor based on sprite stacking technique.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.