1. Blacklisted subject. Sonic.exe spin-offs haven't been allowed for years, thanks to the fact that many of the ones produced are shitty, genuine rip-offs of the original complete with all the cliches it brings. For the longest time, the shitty rip-offs were what made the Sonic category and even constituted about a third of the wiki's pages.
2. You didn't create an entry on the blacklist appeal page. Whereas people have been getting away with this for quite sometime now, it's a rule that is going to start being enforced.
While yours is certainly better than many spin-offs I've seen (ESPECIALLY of exe), it could use some work. But, I will say that it was basically deleted to be even-handed with the rules of the blacklist, not because of its quality in general.