A relative has given us a Hasbro card game called Ratuki - the rules for which can be found here.
I just can't decide how the RATUKI cards are meant to work though. In normal play, a stack must be started with a 1 card, and a stack can only be added to with a card one higher or one lower in value than the current top card. If you play a 5 card to the top of a stack, you shout "RATUKI!" and claim that stack.
A RATUKI card "counts as any number you like" - so you can start a stack with it, and play it onto any stack.
My question is, does a RATUKI card once played keep the value it was played "as"? e.g. if you start a stack with a RATUKI card, is the only valid play on top of that a 2 card? If a RATUKI is played on top of a 2, do you have to specify whether it is a 1 or a 3 and does that information persist (possibly quite a challenge to enforce, in this fast paced game).
The other option is that a RATUKI card can be played as anything and immediately counts as anything. But if this is so, can you essentially slam a RATUKI onto any stack, immediately shout "RATUKI!" and claim that stack? If you start a stack with a RATUKI card, can you immediately claim that stack at the same time?
Are there any card games with an analogous mechanic that shed any light on how the designers probably intended this game to be played?