Have a look over at my Double Dragon 2 Remake here: http://www.designorhea.com/pages/Double_Dragon_2_Remake/

The Demo contains the source code as well, it has a built in combo check (stores keys into an array, based on that plays an attack).
It's not completely what you want, but might give you an idea.

regards,


Formerly known as dennis_fantasy
Portfolio - http://www.designorhea.com/
Project - http://randomchance.cherrygames.org/