Planck Motion Theory (PMT) proposes that motion, time, and energy are emergent phenomena arising from the discrete actions of massless, structureless units called Planck Objects (POs). These units occupy a fixed cubic lattice at Planck-scale resolution and transition between adjacent cells in discrete time steps. This abstract substrate dispenses with the continuum assumptions of classical physics and replacesthem with a minimal, self-contained, and discrete causal structure. Tier 1 of PMTestablishes the foundational geometry and temporal rules of this substrate, introducesthe principle of Planck Motion, and formulates a completeness theorem ensuring that all valid dynamics occur entirely within the closed lattice without invoking classical convergence. This tier provides the axiomatic groundwork upon which all higher-order behavior—including mass, inertia, and wavefront propagation—emerges.PMT aims to unify quantum mechanics and relativity through a discrete causalstructure, offering testable predictions at Planck scales.