Complex sentence: At the time of their closure, the Liverpool studio were reportedly working on a "Wipeout" title for the PlayStation 4 and a "Splinter Cell"-style game; the unnamed "Wipeout" game had been in development for 12 to 18 months.
Split into simpler sentences: At the time of their closure, the Liverpudlian studio was purportedly working on a "Wipeout" title for the PlayStation 4, along with a "Splinter Cell"-style game. The unspecified "Wipeout" game had been in development for 12 to 18 months.