Complex sentence: The system doesn't have an expansion port, which made the Firecore incompatible with the Sega CD, and is also incompatible with Sega 32X, Power Base Converter and "Virtua Racing".
Split into simpler sentences: The system doesn't have an expansion port, which made the Firecore incompatible with the Sega CD. Moreover, it is also incompatible with Sega 32X, Power Base Converter, and "Virtua Racing".