Because the goal of our function is to implement "one swipe"(if this explanation makes the goal clearer):

A given tile can only merge once. (this limits any tile to be summed/combined only 1 time)

Only consecutive letters can be used

exactly

you are right there is a mistake here

Hi, I ran the kata reference solution against the case you've presented and this is the outcome:

starting word: hets

Bob   matches  hets to jets
Alice matches  jets to lets
Bob   matches  lets to ...nothing

(so Alice wins)

So, I'm not sure why you think bob whould win and that the expected result should be -1 other than it is possible you may be reading the feedback off-by-one (the log appears above the test result).

If I understand correctly, I believe this is one of the rules:

'this word cannot have already been used during the game'

Please let me know if I understood your question.

6-7

TW (index 0,1) can form TWO

Where is the O?

Formatting is a little spice on a bland dish...