This could be done either with or without script, but I would just recommend script simply because inventory is not really meant to be used as a regular variable. Either way, you would have to simply set a variable that would decrease each frame (either with a special function that subtracts one from inventory or just subtract one during OnAfterMoveSprites, or whenever you choose) that get's set to, for example, 60 under the following conditions: It is currently equal to 0 and the player has pressed attack. Then, if they player presses attack again, keep track of that (with a boolean variable or a different inventory item). Then, if they press attack and the first variable is greater than 0 and the second variable is also greater than 0 (i.e. true) execute the combo and reset both of the counters. When subtracting from the first inventory, check to see if it's 0. If it is, set the second (the boolean) to 0 as well.