Complex sentence: On the PC, "Diablo"' s effect on the market was significant from the late 1990s: it had many imitators and its style of combat went on to be used by many games that came after.
Split into simpler sentences: On the PC, "Diablo"' s effect on the market was significant from the late 1990s. It had many imitators and its style of combat went on to be used by many games that came after.