7. Justice League Cameos
If the rumour can be believed, that Warner is in some fashion working on a Silver Age prequel that would introduce the Justice League of America, then why not get that ball rolling with some delightful cameos in Arkham 3? It wouldn't need to be anything substantial - and in fact, I'd prefer that it wasn't - but something in line with the Marvel movies, say a cameo during the credits, would be fantastic. What's more, given how much these games favour hidden objects, why not include a few easter eggs around Gotham to be uncovered? What about some references to Metropolis? Or have a newspaper report about The Flash speeding around town? There are a billion different ways they can do this, and while the movie equivalent continues to stagnate, this would be a great way to give fans something to actually look forward to.