Introduce a Little Anarchy

"Introduce a little anarchy. Upset the established order and everything becomes chaos. I'm an agent of chaos. Oh, and you know the thing about chaos? It's fair."-The Joker, The Dark Knight
"Randomness and unpredictability are where improvisation is born."-Clint Hocking, GDC09
Improvisational play is, in a nutshell, the type of play that occurs when a player rapidly and unexpectedly alternates between composition and execution phases. You can read a summary of the idea at Gamasutra and draw your conclusions about its value, but I'd like to show how the stealth combat areas in Arkham Asylum are all about intentional play and maybe needed more improvisation.
The areas I'm referring to share common elements: Patrolling enemies with guns, gargoyles, floor grates. Upon entering the room the player will enter a composition phase. Who will I take out first? How? Timing? And finally, where will I escape to once successful or if spotted? Once the plan is finalized, execution occurs. There are two results: The plan goes wrong and the player must carry out their final escape step prematurely, or the plan goes as expected and the player carries out their final escape step as intended. The enemy weapons are so deadly that if discovered the only recourse is escape. If the escape is successful, Batman will be so well hidden that a new safe composition phase begins. If not successful, Batman dies and the player starts over.
Players may go through several cycles of composition/execution in the course of clearing a room, but the reason this is still intentional play and not improvisational is that the escape step and a return to the composition phase is intentional. Also, as Clint Hocking says in the above quote, improvisation is born out of randomness and unpredictability. It's never random equipment failure or unpredictable AI behaviour that knocks the player out of an execution phase. A skilled player will create and execute a plan that will be successful every time.
This all amounts to a very safe and boring lather-rinse-repeat experience, punctuated by the occasional lather-dammit-restart. Creative play is stunted as there is nothing to throw the player out of the execution phase unexpectedly. When the Joker's men trap the gargoyles with bombs, it is revealed in a cutscene. The player figures out how to deal with them from the safety of the initial composition phase. Imagine if the bombs had not been revealed in a cutscene. What if the player grappled to a gargoyle at the end of their execution phase, expecting a return to safety, but found a ticking time bomb instead? Or what if the enemies started randomly using flashlights and scanning the ceiling, or opening floor grates, during their patrols? This could potentially lead to improvisation and, I believe, a more rewarding stealth/combat experience.
I'm not suggesting removing a cutscene of bombs being attached to gargoyles would suddenly allow improvisational play that was fun. Like most good design, it requires a holistic approach. One of the key ways Far Cry 2 prevented the jolt from execution to composition from annoying the player was with the "free life" afforded by the buddy. Sometimes an unlucky series of random events kill the player outright instead of dumping back to composition. For the chaos of improvisational play to be fair, a second chance is sometimes required. If Arkham Asylum were to support improvisational play it would need a system of forgiveness similar to Far Cry 2's. Remember the first scene of Tim Burton's Batman (skip to 2:00 mark)? Feigning death every once in a while as the suit performs defibrillation or adrenaline injections could provide an opportunity to improvise a new plan.
In any case, I don't want to redesign the game here, just suggest the stealth combat areas would have been more engaging if they embraced improvisation. Batman exhibits extraordinary improvisational skills in the cutscenes, such as spraying explosive foam on his glove for devastating punch and setting a trap for an enemy he can't defeat in hand-to-hand combat. I wish the stealth area design challenged us to be as spontaneously creative as Batman appears to be when we're not in control.