All suggestions are considering a right-handed character.
Hands:
Mouse clicks:
Right button: right punch.
Left button: left punch.
Left button + right button: punch with both hands, which could serve as a push.
Pressing the mouse:
Press right button: right cross.
Press left button: left hook.
Pressing left + right button: arm a guard that blocks physical attacks, being effective only with punches / basic zombie attacks, consumes istamine to maintain, can be broken.
While jumping:
Clicking / pressing on the right and left mouse buttons keeps the punches, hook and cross, pressing the left + right keeps the guard, but just clicking on both at the same time triggers a kick, it is much more powerful and has the effect of a push.
While holding a melee weapon (baseball bat, axes, swords, etc).
Clicks:
Right button: Basic attack 1 (I am considering the ax movement in the beta).
Left button: Basic attack 2 It could be an attack in different positions, diagonal or vertical, taking more damage.
Left button + right button: push.
Pressing the mouse:
Press right button: Basic attack 1 receives a charge that consumes histamine, but delivers a much stronger blow.
Press left button: Basic attack 2 receives a charge that consumes histamine, but delivers a much stronger blow.
Pressing left + right button: Mounting a guard much more efficiently than using only your hands.