How cool would it be to have x-men and Spider-Man one shots? Have them be extended length one shots and all the villains be manditory to defeat before progression. For X-men you have to kill a bunch of sentinels before reaching the brother hood then you fly to the savage land where you then dinosaurs and kill sinister then progress right to apocalypse etc. For Spider-Man have it be New York and you gotta kill sinister six then venom and carnage. Maybe then travel to alternate universes where you have to defeat different spidermen.
I also think doing a secret wars one shot would be great as well. Extending the length of the one shots to 45 mins would really make completion so much more satisfying. Maybe do bis items for zero deaths and completeing them under a difficult time? Just some ideas.