Prince of Persia came out in 1989, while Flashback arrived in 1992. In the late 80s and early 90s, pc video game tech was evolving at a breakneck pace, a 3-year gap was an eternity. Prince of Persia ran quite well on an 8-bit XT, Flashback needed a 16-bit 286. They are basically from a different era, and Flashback was surely inspired by PoP.