From what I can tell, there's nothing else that can open a .AEP file besides After Effects because most of the information is only usable in After Effects. The other effect and video editing software options all have a different focus than AE, so to get something that does exactly the same thing, you'd need more than one of them. I'm struggling to explain this, um, it's like using an apple slicer to open an orange I guess. They may both be fruit but the insides are very different.
Besides my Might and Magic inspired project, I have always wanted to make a Fire Emblem-like game. Time is the culprit... Between life, composing music packs, and working on a game can it be done!? The tactical plugins for MV work quite well based on what I have tested.