Translation:Because of the rain the game has become difficult
I wrote, because of rain the game has become difficult, and they say the answer is, because of rain thegame has become difficult?! What's the problem with this?!
It's an error due to the missing space (thegame) in the 'correct' answer - just report it as an error.
One of the hover hints was "has failed to materialize". That seems more likely here, as in "the game was cancelled".
Still, I suppose you might carry on playing up to your knees in mud. I wonder how people know which one you meant.
The tips for the lesson teach about the "-ika" sufix but why is there an extra "-na" tacked on the end of "umeshindikana"?
It just happens that a handful of stative verbs are formed by adding the reciprocal ending to the usual stative ending. Three examples are given in the notes, although there is no discussion. The ones I can think of off-hand are: -onekana (seem/be visible), -semekana (be said that), -patikana (be available/obtainable; be found), -wezekana (be possible); -shindikana (be unsuccessful; fail to materialize). There are probably a few more. In these cases, the corresponding -ika/-eka verbs tend to be used infrequently, but may occur. One example: mambo yasiyosemeka - things which are not spoken of (or cannot be spoken of).
Can't find any translation for -shindikana online that means "become difficult". Found: (1) fail(ed); (2) get stopped; (3) be unsuccessful or inconclusive. https://translation.babylon-software.com/swahili/shindikana/ https://glosbe.com/sw/en/shindikana https://sw.oxforddictionaries.com/ufafanuzi/shindikana