We're just the tiniest bit late in getting to this one (how shocking), but hey, we got there! Looks like the developers behind the game ManeQuest have given the fandom yet another neat little colorful horse creator, this time with a nice looking (those eyes are a bit creepy though, tbh) pixel art style that's just a tad more...er, "artsy-looking," I suppose, than the similar pixel-style creator for Pony Town.
While I haven't had the time to dive into this one personally, it appears that from the looks of the ponies posted by folks in the comments on the game's
DA page and elsewhere, this'd be the creator to go with if you felt the need to create your own Personal Pixel Poner™!
6/20/17: So I've finally had a little bit of time to check this out for myself, and I figured I'd edit in a more developed opinion (I'm not a fan of posting things before I've had a chance to test them out). It's not bad, but it is a little lackluster considering there's no actual game attached to it yet. Additionally, I think I'm definitely more partial towards Pony Town's creator insofar as comparisons go, mostly because Pony Town offers more customization options (which is handy if you're aiming to recreate your Donut Steels from tip to toe), plus that game's ponies are just generally cuter, haha.