How do you determine which attacks are being used? Is melee tied to a single button, or multiple (or combinations of)? Or is the move dependant on the actual scenario (range, position, etc)?
There is only one attack button for unarmed attacks. Attacks change based on Mike's state (standing or walking vs. running), the enemy's state (hostile vs. unaware or stunned) and length of button input (tap vs. hold). Standing/walking Mike vs. a hostile enemy will perform a hard strike with a held button, and will perform chained hits with taps. The chained hits are randomized linked combos. So there may be a total of five hits in combo A and five hits in combo B. When you start the chain, it randomly picks between combo A and B, though you are still giving individual inputs for each attack -- so you can stop whenever you want. But once combo A starts, it will only use combo A attacks unless you let the chain expire and start a new sequence.
Ah, okay. Simple enough, but still providing a decent variety (at least, compared to other titles where melee basically means one attack). Tap vs hold is a nice touch.