It's really new like only three minutes old, here's what I got.

It starts off after you collect five crystals. The party believes they've saved world, but the secret is that the crystals were traps. Only the strongest heroes could retrieve the crystals, so an entity or rather five entities were sealed and are now released. They now posses all but one of the main characters. Now the survivor flees for his life, going into hiding.

That's it. Don't know anything else after that. So is it ok? Is it cliche? This could be my story for rpg maker 3.

That's an interesting plot. I was about to say that it was cliche, but the twist that the heroes get posessed by the crystals gives it the twist it needed. Hopefully you can get a story just as interesting together.