A7 have power, but also have limitations. A gears of war clone, as any other game clone, is possible to be made but each feature represents a more or less difficult challenge to implement.
The Shaders features in A7 are the first visible limitation: to fix shaders in an A7 title you need to follow a lot of extra steps described in several threads on the forums. Them, there's the AI... usually strong mainstream titles uses things like Alienware for artificial AI, but you can fake some Artificial inteligence with real Natural Dumbness since NPC behavior is all about your position and what are you doing.
It's a tradeoff: while you can swamp a level with position detectors and behaviors, using more advanced code will require less time in the assembling.
Meaning: A7 can do virtually any kind of game, but some features are better left aside because of increasing code complexity.