Complex sentence: Players were able to connect with other Silent Hunter II players, and engage in sub vs. sub combat; also, connectivity to the separate game Destroyer Command (also released by Ubisoft) was available, which enabled sub and surface ship combat.
Split into simpler sentences: Players were able to connect with other Silent Hunter II players, and engage in sub vs. sub combat. Furthermore, connectivity to the separate game Destroyer Command (also released by Ubisoft) was available, which enabled sub and surface ship combat.