This paper focuses on the competitively optimal power control and signal shaping for "ad hoc" networks composed by multiple-antenna noncooperative transmit/receive terminals affected by spatially colored multiple-access interference (MAI). The target is the competitive maximization of the information throughput sustained by each link that is active over the network. For this purpose, the MAI-impaired network is modeled as a noncooperative strategic game, and sufficient conditions for the existence and uniqueness of the Nash equilibrium (NE) are provided. Furthermore, iterative power-control and signal-shaping algorithms are presented to efficiently achieve the NE under both best-effort and "contracted QoS" policies. The presented algorithms also account for the effect of (possibly) imperfect channel estimates available at the transmit/receive units active over the network, they are fully scalable, and they may be implemented in a fully distributed and asynchronous way. The presented numerical results support the conclusion that the proposed distributed algorithms may be able to outperform the conventional centralized orthogonal MAC strategies (as time division multiple access, frequency division multiple access, and code division multiple access) in terms of a sustained network throughput, especially in operating scenarios affected by a strong MAI