In this intricate examination, the noncooperative game theory framework of decentralized unmanned aerial vehicles (UAVs), circumscribed by rigorous task constraints, is explored. We have ingeniously crafted a novel time base generator (TBG), which empowers all UAVs within the decentralized system to converge harmoniously towards a generalized Nash equilibrium, all within a predetermined temporal horizon. Remarkably, this convergence timeline can be meticulously calibrated prior to execution, unfettered by initial states or intricate design parameters. Subsequently, we leverage the Lyapunov techniques to rigorously demonstrate that our proposed approach converges precisely within the predefined time frame. Ultimately, we conduct numerical simulations to validate the efficacy and robustness of our proposed algorithmic framework.