Great Game. Also had an idea for the same game. Was a bit confused about your "stacking"-rule. But found out. In my game you would be allowed to "stack", or play more than one card at a time. For ex. you have 3 cards at any value, you can play them in the order you choose, ending in a preferred color.
Also playing more than one "reverse", STOP, "+2", "+4" cards.
Ran into the problem showing more than 7 cards, and never got any further. Hope to get back to it soon.
Thanks for the game :)