Patchwork

Lyra Deighton is a high school student at Tri Valley High, who, despite being a completely weird (read: fangirl-y) person, is actually normal as far as encounters with the supernatural go. That is, until her art teacher hands her a dusty video game that looks like it was made way before video games, and tells her to play it. Lyra thought it was just a weird way of showing affection, but it's so much more serious than that. The game contains things that Lyra has never seen before, never heard of before, and definitely has never fought to the death before.
Get ready, because all the universes are about to open up.