Thanks for your feedback, the description says:

Java, C#:
'game' returns a string that mimicks an array

I thought it meant: "'game' returns a string that mimicks the array returned by the other languages". I'll change this part.

You are welcome!

Seems that your encode function is right until test8, maybe your decode function? I don't know what to say... Maybe take the other kata and see what you get?

For the time being, Codewars times out constantly:-( It needs a break!

Please can you tell which language and be more explicit about

"I got a lot of question marks that would not return the correct sentence"?

I can understand your sentence:-(

"i?" can't be a prefix.
PS: did you do the "first variation on Caesar Cipher"? (http://www.codewars.com/kata/5508249a98b3234f420000fb)