The huge MMORPG Legends of Equestria is hosting their open server weekend right now! You can make your OCs and explore the maps to your hearts' content.
To download the game, click the link above and navigate your way to the proper download link for your operating system. IF you don't already have a forum account for the website, just whip one up quickly.
If any of you are interested in playing with me (Callilian), don't hesitate to respond or send me a PM. I'd be happy to go exploring with you. And, if you happen to stumble across Sherlock Holmes or Ebony LeBrun flying around a map, just say hello! (Yes, Ebony's a unicorn, but the pegasi are so much more fun to play with!)