From Sonic Retro
History of Sonic the Hedgehog ZX
eggboyX0 started working on Sonic the Hedgehog ZX with his older brother CarrascoZX0 in late June of 2007. Sonic the Hedgehog ZX started out as a layout and palette hack (This was mostly because both brothers didn't know ASM at the time). But soon after their second release on the SSRG's Hacktube the hack was canceled (It's sometimes very hard to work with your family).
Even though eggboyX0 doesn't help his brother work on Sonic the Hedgehog ZX anymore, he continues to support his brother into finishing his hack. On April 14, 2009, Sonic the Hedgehog ZX was put on hold due to the fact CarrascoZX0 doesn't have a computer to work on his hack with.