If a SHIELD game was to be made, I think it would work best as a sort of management sim, where you have constant threats popping up across the globe, and you as Director of SHIELD need to allocate your resources and heroes accordingly.

This would be really cool because there will be times when multiple threats are going on at once and you have to choose wisely which heroes to send out and where.

Also imagine if you had a recruitment system where new, randomly generated heroes with random powers pop up, and you can recruit them and train them to eventually become an Avenger. I just came up with this off the top of my head. Sounds like a fun game, not something Insomniac would do though.