Delta Time, it's a feature inside the engine. Delta time means a space of time between 2 point in a time line.
You can reproduce your request following this procedure:
- Create a number variable inside your instance (instance is the sprite object) and call it as "combo";
|- On keyboard "A" is pressed (for example);
|- If "combo" = 0;
-- Play the animation "punching1"
-- Add 1 to "combo";
- On animation "punching1" is finished:
-- Set "combo" to 0;
|- If "combo" = 1;
|- On keyboard "A" is pressed;
-- Play the animation "punching2"
-- Add 1 to "combo";
You can loop it, make different animations for each stage of the combo, or just repeat the combo animations, this way:
|- If "combo" > 0;
|- On keyboard "A" is pressed;
#when you have one animation for each combo sequence;
-- Play the animation "punching" & player.variable.combo;
#when you have two animation at all;
-- Play the animation "punching" & random(1,2);
-- Add 1 to "combo";
Don't miss to reset the "combo" variable to 0 when the "A" is not pressed by 1 or 2 seconds.
That's it. ^^