A sonic fan was annoyed they couldn't play Sonic Unleashed on PC so built the system within 6 months
Sonic Unleashed has been used to prove out the system
Non-technical explanation: Opens the door for native PC ports of Xbox 360 games, akin to N64 Recompiled (which was used to make Zelda 64: Recompiled). A lot of manual work and technical knowledge of recompilation is still required but this is a huge moment for the game preservation community.