Complex sentence: Codemasters developed a quasi-multitap for the Mega Drive called the J-Cart; the game would have two extra joypad ports built into the cartridge itself, thus negating the need to buy extra hardware (beyond two more joypads) to play four-player games.
Split into simpler sentences: Codemasters developed a quasi-multitap for the Mega Drive called the J-Cart. The game would have two extra joypad ports built into the cartridge itself, thus negating the need to buy extra hardware (beyond two more joypads) to play four-player games.