My Little Pony: Rise of Vicis

...One day, [...] the Mane 6 mysteriously lose their cutie marks after a sudden shockwave of energy. Looking into the sky, they see a dark portal open into another world. It releases little creatures that start terrorizing the town. Then, the portal vanishes.
As they ask around town for what happened, nopony recognizes them or knows who they are. They proceed to Canterlot Castle to ask Princess Celestia, who doesn't know who they are either. She tells them of a great inventor who lives upon a floating island far from Ponyville who can help them.
Upon their arrival, they meet Silvercog. He explains that a great evil is trying to escape from a dark realm, and the shock wave that rid the Mane 6 of their cutie marks was the evil trying to escape. That evil is called Vicis, the Time Wraith.
He says they need to find the Elements of Harmony in order to seal Vicis within the dark realm. Silvercog had built portals to take the Mane 6 to different parts of Equestria to search for the Elements. And so, the adventure begins...

MLP: Rise of Vicis is a work-in-progress My Little Pony: Friendship Is Magic fan game created by Negation Squared. It features six different spins on the Platform Game genre - one for each playable character.

The official tumblr can be found here.

Tropes used in My Little Pony: Rise of Vicis include:

Big Applesauce: Manehattan.
Capital City: Ponyville.
Casino Park: Trixieland.
Double Jump: Pinkie Pie is the only pony that can do this.
Egopolis: Trixieland.
Eternal Engine: Mechanica, though it's a Hub Level.
Evil Knockoff: Storm Dash, of Rainbow Dash.
Gadgeteer Genius: Silvercog.
Green Hill Zone: Ponyville.
Hearts Are Health
Hub Level: Mechanica.
Names to Run Away From Really Fast: Vicis.
Platform Game: With several subtypes; Pinkie's gameplay is this, for starters.
- Puzzle Platformer: For Rarity.
Ret-Gone: While they don't cease to exist, Vicis attempting to escape the dark realm did this to the mane cast.
Sealed Evil in a Can: Vicis trying to escape his can is what caused the whole mess in the first place.
Sprint Meter: Rainbow Dash has one.
Temporal Paradox: Part of the main story; the mane cast have been essentially erased from the populace's mind thanks to Vicis.
Time Master: Vicis.