Sinistron (1991)

Scramble Mode Zeta; A message to Cybernaut Squadron Calisto -- Priority Alpha-San 03... An intersystem intruder has been detected in quadrant FTU-770. Dronecraft sent to get a visual discovered an extremely large monolith, biomorphic in nature. All attempts at contact ended in destruction of drones. Your mission: locate, intercept and enter the Sinistron. Use any means to destroy it!