Complex sentence: Thunder Force IV was the very first game with a sophisticated regional lockout chip, meaning that unlike previous Mega Drive games you could not play the Japanese version on a European Mega Drive or Sega Genesis (and vice versa) with a simple pass through adapter.
Split into simpler sentences: Thunder Force IV was the very first game with a sophisticated regional lockout chip. Unlike previous Mega Drive games, the player could not play the Japanese version on a European Mega Drive or Sega Genesis (and vice versa) with a simple pass through adapter.